It implies that the person being persuaded is not enthusiastic about doing the thing but is eventually convinced, often because of pressure or incentives.
Here are some examples of how the idiom is used:
* "I didn't really want to go to the party, but my friends twisted my arm."
* "He offered me a promotion if I agreed to take on the extra work, so he really twisted my arm."
* "She didn't want to lend me her car, but I managed to twist her arm."
The idiom is often used humorously to indicate that someone feels pressured into doing something they would prefer not to do.