I am looking for fonts to use for a bound planner of sorts that I am making for myself, but possibly to sell in the future. I've downloaded a few free fonts, with SIL open licenses, can I use these? Thanks!
The full license of OFL can be found here. SIL OFL license is a somewhat permissive copyleft license. Itis unfortunately a viral license. So it is not entirely suited for every action. It is however not similarly viral as using GPL:ed components as it only affects the font itself and leaves rest of your stuff intact.
To be clear. In the usecase that you describe it seem perfectly fine. But i am not a lawyer, and not your lawyer so dont take this as legal advice.
There are other permissive font licenses other permissive font licenses such as:
When in doubt, read the license
[SIL Open Font License] enables font authors to release their work under a common license that allows use, bundling, modification and redistribution.
That's about as open as it gets.