Lesson One:

In Esperanto, words are built. They consist of a root word, then the part of speech.

Nouns end in -o.

Here are some examples:

cato = cat
hundo = dog
libro = book
viro = man
knabo = boy
filo = son
breto = shelf
planko = floor
plafono = ceiling
muro = wall
porto = door
fenestro = window