Not OP but gonna explain a bit about it nonetheless:

Other than the US use (generally meaning anarcho-capitalist, selfishly ignorant or both), libertarian is just the opposite pole of the "how much do we let people control us" axis from authoritarian.

So basically a left-libertarian (which is a big spectrum of different political philosophies) is broadly speaking someone who doesn't believe in inherent authority but DOES believe in rules and various degrees of enforcement to defend the powerless from the powerful.

Well, typically other libertarians like to pretend we don't exist and invoke the magic phrase "you're not a real libertarian", whereas left libertarians prefer to pretend that there's more than one of us. The tl;Dr is that it's more of anti-authoritarian take than a pro-free-market take that you'd get from right lib.

On the matter of economics, I believe that free markets work and work well where they exist, which is certainly not everywhere they're imagined to. In other words, I'm not willing to imagine that markets with baked-in coercion (like healthcare) are free. Free markets require choice and, ultimately, the ability to say no without coming to harm. If I can buy a widget from Bob, a widget from Sally, or not buy a widget and suffer no cost or harm, that's a free market. I also generally don't believe in rugged individualism; poverty is, itself, a coercive force in economics. This sort of view is partly how I wholeheartedly endorse mass transit and good urbanism as a libertarian, because being functionally coerced into car ownership isn't economic freedom.

I also believe that the government does have a right to interfere with gross negligence. That is, if you're drunk driving, if you're having a bonfire and there's a high wildfire risk, or you're doing something that any reasonable person would understand is an imminent danger to the safety of others around you, the government has an absolute right to make you stop. Most right libertarians think that the government should only interfere with direct violence and that everything else can be settled in court; so basically, if you're a drunk driver, make sure you kill whoever you hit so they can't sue you. I also think that this applies to companies and organizations, not just people.

Those are, probably, pretty uncontroversial takes, and you might be thinking "so where's the libertarianism?". Well, I also think that the government has massively overstepped its bounds, especially in the last forty years or so since Reaganism. Ready? Here we go. The war on drugs and the war on terror has seen the government giving itself ridiculous powers that need to be culled immediately. The NSA mass surveillance program (which was 'killed' by the SCOTUS and resurrected by Obama and the Republicans under the cynically-named USA FREEDOM ACT later that same day) should be erased in totality. The government should not be collecting any data from any tech company on anybody without consent, a warrant, or the data being anonymized (if it's, for example, for research purposes). The patriot act should be repealed yesterday, and gitmo should be closed because holding anyone without trial is wrong, full stop. No-knock raids should not happen, period, and we desperately need police reform. The entire country is a free speech zone, and protests should not be met with brutal crackdowns. I also think that what happens between consenting adults or what a consenting adult does to themselves is nobody else's business, as long as it's without coercion. That's maybe 5% of the rant I could go on, but I don't want to write a book, and I don't think you want to read one.

Also:

-What happens between consenting adults is nobody else's business, least of all the church or the government. I'm pro sex work and pro LGBT rights.

-I'm pro-abortion rights.

-The government needs to leave the native Americans the fuck alone. 2023 and we're still fucking with them. The government needs to leave everyone alone, but they particularly need to fuck off on native Americans. That said, I think we should still financially support their recovery as a people and culture from what we've done to them, but they should get to decide the shape that takes, not us.

-I'm firmly against borders. If it was up to me, I'd Thanos snap that shit. No more borders. I know that's an extreme position, and I'd be willing to compromise for an EU-style open borders arrangement.