Mons Agnes is a hill , in Lacus Felicitatis, inside crater-like feature Ina, in Lacus Felicitatis, inside crater-like feature Ina,. Its height is more difficult to determine; from Apollo 15 images it was determined as about 30 m, but newer map, based on LRO photos, gives about 10 m. Mons Agnes was discovered on the photos made by Apollo 15 from lunar orbit in 1971. In 1974 NASA published a topophotomap where its name first appeared: it received Greek feminine name Agnes. (wikipedia entry)
A mons is a mountain. On the Moon they are named after terrestrial mountain ranges, nearby craters, and deceased scientists who have made outstanding or fundamental contributions to their fields.