Yavin IV is the planet that the Rebel Alliance plan their attack on the first Death star. The filming for the scenes was done in Tikal National Park, Guatemala. After the destruction, the Rebels leave the planet and hide out on Hoth, the Ice World.
The character Poe Dameron comes from Yavin IV. The producers added the Poe touch because the scenes were set in Guatemala and that is where Oscar Isaac was born.
The film makers returned to Yavin IV for the first spin-off film in the Star Wars anthology. We see more of the planet, the Mayan buildings of yesteryear. Although some of the buildings are C.G.I. with the original buildings in a little.
The base commander is Mon Mothma, there is no Princess Leia. On the planet we see a brief cameo from C-3PO and R2-D2 as the rebels take off for their mission to steal the Death Star plans against the wishes of the Rebel Council.
Yavin IV Base is a giant pyramid but we only see that in Star Wars - Rogue One. In the first film (A New Hope), all we see is the skyline and the entrance to the base. We see more of the base in Rogue One.