This is the Tunnel View, probably the most famous vista in Yosemite. It's bookended by El Capitan on the left and Bridalveil Fall + Cathedral Rocks on the right. In more settled weather you'd also see Clouds Rest and Half Dome off in the middle distance. From this vantage point, Yosemite Valley appears to be a solid mass of trees, but there are actually meadows running much of the valley's length, and the Merced River is down there somewhere too.
The Tunnel View is justifiably crowded during the summer months (this Google Street View shows a fairly typical scene), but more manageable during bad weather, when it's often more dramatic looking anyway. If you want a Tunnel-View-like scene in the summer without Tunnel View crowds, try hiking to Artist Point. Its trailhead is just across the road from the Tunnel View.