If only I could collect a dime each time these three words were mixed up!

Borrow means to take something with the intention of returning it: Jane asked Jim if she could borrow his pen.

Lend means to grant permission to someone for taking something, with the understanding that it will be returned: Jim told Jane he would lend her his pen.

Loan means to turn over something to someone for their temporary use, usually with the expectation that interest will be paid: The bank would not loan money to Jim so he could start an ink pen company.