Hi Callieco! That is a strange looking fitting. The white fitting appears to be a SeaTech or FlairIt fitting that most plumbing and RV shops have in stock for small repairs. The silver colored elbow is a bit odd looking. Many people have had good luck with these and the "Shark Bite" fittings that are sold at Lowe's and Home Depot. With Shark Bite fittings, you'll have to cut it with a straight cutter and replace the damaged section of tubing and fittings. There are many good threads to read about PEX plumbing here on the forums.
Work is never done, so take time to play!