Why do Muslims perform Wudu before prayer?
Wadu is a way of purification of you before standing before
Allah the almighty. Islam urges people to be always clean, neat,
smart and with nice odor "perfume". To be clean and tidy is part of
Islam.
Before you eat you usually clean your hands for example!
and before you are ready to stand and talk to your creator Allah
the almighty, you make Wadu. This is your ticket to start prayers
and communicate with Allah subhanahu wata'ala.
Wadu also as it purifies you from dirt, it also purifies you
from sins. (small sins not deadly sins) which need honest
repentance.