Rain :)

I love that feeling when it rains
When it falls on the plains
Cuz I can run in vain
I let it saturate my clothes
And then wait for it to drain
Maybe it can wash away my pain
When it falls on my head
I feel a flirtation with my brain
When it falls in my eyes
I feel as if it says:
(Don't cry again…
Trust GOD & wait for what you'll gain…)

I love that feeling when it rains 

When it falls on the plains

I fall / you fall / he falls / she falls / it falls

I can fall / you can fall / he can fall / she can fall / it can fall

'Cuz I can run in vain
I let it saturate my clothes
And then wait for it to drain
Maybe it can wash away my pains 

When you talk about emotional pain, then the word is generally singular. If you talk about bodily (physical) aches and pains, then the word can be singular or plural.

When it falls on my head
I feel a flirtation with my brain
When it falls in my eyes
I feel as if it says:
(Don't cry again…
Trust GOD & wait for what you'll gain…)

I would remove the parentheses ( ) and use italics to highlight the last two lines.

Thank you for sharing a beautiful poem!