Learn Hardcore Latin: Altitudo magna est.

Altitudo is a noun meaning height, depth, or altitude/elevation, depending on context. In this sentence, since the meaning has already been given, you can understand it as height.

It is the kind of abstract noun English often forms with -ness or -ity. So you can think of altus (high/deep) becoming altitudo (height/depth).

Why is there no word for the or a?

Latin usually does not have articles like English the and a/an. So Altitudo magna est could be translated as:

The height is great
A height is great
simply Height is great

Which English version sounds best depends on context. Latin often leaves that unstated.

What case is altitudo, and how can I tell?