This is the 323rd most frequent Estonian word.
kaitse
"Defense" or "protection."
Here, 'kaitse' is used as a verb in the imperative mood, meaning 'protect'.
Kaitse oma sõpru alati.
Always protect your friends.
The word 'kaitseme' is a form of the verb 'kaitsma' (to protect), presented here in the indicative mood first person plural, meaning 'we protect'.
Kaitseme üheskoos loodust.
Let's protect nature together.
In this sentence, 'kaitse' is used as a noun, representing 'protection'.