I have a bump in my lower eye, below lower eyelash. My doctor said that it's infection and I have to operate it. Its not itchy nor pain. Just a bump?

Chalazion. This is a congested oil gland, hot/ warm compresses on the lid bump for 10 minutes and 3-4 times a day may help initially. If it gets bigger or is very bothersome then it can be drained as an in office procedure.
Chalazion. Your description sounds like a chalazion. These are treated with warm compresses, antibiotic/steroid topical medications. If no improvement, intralesional steroid injection or excision may be needed. If the bump does not bother you, it can also be observed.