Hello so me and yes man took over New Vegas strip and for one of his quests i have the option to tell him if i want to ignore a faction. I dont really know what ignoring them does. I am with the B.O.S so should i ignore them so they wont get hurt? please help!

It's just yes mans way of saying to choose if you want that faction on your side at the end of game. Ignore the ones you don't want, do the ones you want.