The Suffix -an

a member of, someone belonging to:

• klubano – club member
• amerikano – American
• samlandano – fellow-countryman
• samideano – fellow-supporter of an idea (in particular, a fellow Esperantist)

The Suffix -ec

makes an abstract noun — a state or quality:

• beleco – beauty
• varmeco – warmth
• simpleco – simplicity

💡 Memory aid: -ec works like English "-ness" or "-ity":

• bela (beautiful) → beleco (beauty)

The Suffix -uj

forms the name of a container, a country or a plant:

• manĝujo – manger, food-trough
• cindrujo – ashtray
• Francujo – France
• Aŭstrujo – Austria
• pomo (apple) → pomujo – apple tree