Question

how does eggs fertilize in humans​

Answer 1

When male sperm fuses with female ovum or egg it fertilise

Answer 2

every month single ova released to uteres via oviduct or fallopian tube.

if semen were released. one sperm touch that ova and fertilization occur and zygote form.

you can stop it by use contraceptive devices

physical barrier: condom, cervical caps, t loop

oral pills: it will stop producing ova for certain period. but, more disadvantages are there

surgerical:

blocking fallopian tube(tubectomy)

blocking vas defernas (vasectomy)

I hope my helping hands will help you my friend.