John Gill Commentary 2 Kings 5:2

"And the Syrians had gone out in bands, and had brought away captive out of the land of Israel a little maiden; and she waited on Naaman`s wife." — 2 Kings 5:2 (ASV)

And the Syrians had gone out by companies
Not regular troops, but a sort of banditti of robbers, which made excursions into the land of Israel, to plunder and carry off what booty they could:

and had brought away captive out of the land of Israel a little maid ;
for boys and girls were a part of the booty of such robbers, whom they could sell for money, see (Joel 3:1) . Jarchi and Kimchi say she was a girl of Naaron, a city so called:

and she waited on Naaman's wife ;
being either made a present of to the general by those plunderers, or was bought by him of them for his wife's service.