can someone help me to learn punjabi?

salaam

if i follow this example :
I DIDNT UNDERSTAND = mainu samajh nai ayee

I UNDERSTAND = main samajh gaya (if female then ‘gayee)’

so when we say here :
I DONT KNOW = mainu nai patta

so
i know : main patta

right ?

but here u said :

I LIKE IT = mainu passand ae

I DONT LIKE IT = mainu nai passand/ mainu nai
achha

why we say MAINU PASSAND AE : I LIKE IT

why we dont say : MAIN PASSAND AE
what is diffrence between : main and mainu ?

thanks