Trying to replace a Trailer's kitchen faucet
It looks like you need a 3/8 to 1/2” male to male adapter take the larger piece to a plumbing or big box store to make sure you get the right sizes but you will will need a 1/2” nipple a 3/8 nipple and a female reducer from 1/2” to 3/8 and some pipe dope or Teflon tape to make the transition. You may be able to get push on fittings also but the nipples may be cheaper and quick.