Verified answer

Firstly, it's not 'aline'. It's 'a line'. Two words. If you want help, you're going to get correct help from me.

'Drop someone a line' means to write them a short letter.

"I must remember to drop Grandma a line and thank her for the birthday gift she gave me."

"I must remember to drop Jill a line. It's been ages since I heard from her."

"If you have a few minutes to spare, drop me a line."