In general, you can copy and create your own works for personal use as long as you keep them to yourself. Copyright is usually enforced on distribution, so if you don’t distribute, nobody cares.
Free licenses (MIT, GPL variants, Apache, BSD, and so on) allow you to copy and create your own works and distribute the work freely. Free licenses allow you to distribute your work if you share the source code, and some (MIT, Apache, etc) allow you to distribute the work even without sharing your source code as long as you provide the source code for whatever was licensed (like a library you’re using that’s MIT licensed).
The licenses all have different restrictions, so it’s good to research a license before you use something licensed that way. For example, AGPL, GPL, and LGPL are all different, and some licenses may require you to rename and rebrand something if you create a fork of it.
While not legal advice:
In general, you can copy and create your own works for personal use as long as you keep them to yourself. Copyright is usually enforced on distribution, so if you don’t distribute, nobody cares.
Free licenses (MIT, GPL variants, Apache, BSD, and so on) allow you to copy and create your own works and distribute the work freely. Free licenses allow you to distribute your work if you share the source code, and some (MIT, Apache, etc) allow you to distribute the work even without sharing your source code as long as you provide the source code for whatever was licensed (like a library you’re using that’s MIT licensed).
The licenses all have different restrictions, so it’s good to research a license before you use something licensed that way. For example, AGPL, GPL, and LGPL are all different, and some licenses may require you to rename and rebrand something if you create a fork of it.