Permissive licenses permit a broader range of use compared to “copyleft” licenses.
“copyleft” here just being a cute way of being the opposite of copyright - instead of disallowing others from what they can do with “copyrighted” code, “copyleft” requires that they (upon request) share modifications to your code.
Permissive takes away this requirement to share your modifications. “copyleft” is considered more free and open source (FOSS), permissive is more business friendly.



A few often overlooked ways to contribute:
Even if not code, some of these are quite specialized. Just be realistic about where you can add something useful.
For all of these, it is critical that you first contact the maintainers and ask what they would find useful. Be mindful that it’s also work for the maintainers to manage your help. The only “wrong” way to participate in open source is to drop a bunch of work on someone unprompted.
Generally, if a project already has a clear call for contributions or a contribution guide, that is a good indicator that the maintainers are willing to do a bit of community management to bring in help. I would only suggest investing energy in those projects if you have the choice.