Question

can someone pls tell what's oxidation and reduction

Answer 1

oxidation is process in which oxygen is added to an element or a compound or reduction of hydrogen
reduction is the reverse of oxidation

Answer 2

When electrons are lost, oxidation occurs and when electrons are gained reduction occurs. Here's a mnemonic sentence to remember this difference:
OIL
Oxidation
Is
Loss
RIG
Reduction
Is
Gain