ナンパ - seducer, ladies' man, playboy された - passive form + past tense of する
1 Answer
Depends on the situation but the possible meanings are:
"I got hit on."
"I got picked up."
"A guy tried to pick me up."
The reason that I said the meaning depended on the situation is that the phrase 「ナンパされた。」 says nothing about the result -- that is whether the guy was successful or not.
In the original 「ナンパされた。」, the unmentioned subject would usually be "I", "She", "They", etc. It is the woman/women who got hit on.
Extra Info: When a woman tries to pick up a man, that is called 「[逆]{ぎゃく}ナンパ」 -- 「逆ナン」 for short if you want to sound more street.