To "give pointers" means to give someone little bits of advice.

You're not holding that quite right. Do you want me to give you a few pointers?

You can give someone pointers on things like:

• some sports technique, like throwing a ball or shooting an arrow
• how they cook something
• how they deliver a speech
• how they answer questions in a practice interview

"Giving pointers" is usually a positive, helpful thing. When someone gives advice that you don't want, you can instead say that they are "nitpicking" or "criticizing" you.