Looks like crabgrass. You can spray a post-emergent on it and/or pull it by hand. Best to kill/remove it before it goes to seed, so it doesn't come back next year. Also, you may look into a pre-emergent next spring. I use Lesco Dimension with great results.

Did it just come up in the last month or two? If so probably crab.

Could be quack grass or goose grass as well. Whatever it is, I just spray it with Acclaim from Lesco. Sometimes it takes two applications though. I started seeing this exact thing popping up when it was too early for crabgrass.

The only thing with Acclaim is it's about $80 for a 16oz bottle. But, at least for me and how much I'd have to spray, I only use .50oz per gallon, and usually only use one gallon twice per season at the most. So that 16oz bottle will last me for quite a long time theoretically. Long enough to average out and have it be worth the cost.