If I got a minor stab in my foot what would be some signs to know if it's infected or not?

Few signs... Look out for increasing redness, swelling, pain, possible pus collection/discharge etc..If severe, you may have fever as well...If these symptoms are getting worse, likely you are having an infection. If the stab wound is getting less painful, less redness/swelling, that is a good sign that it is getting better. If you are concerned, see your doc... Good luck.
Infection. There are five typical features of an infection. These are pain, redness, pus, fever and swelling. If all of these symptoms appear at the same time, then it is most likely infected.