3rd Declension
Caupo of Turaida died in 1217.
No, it means 'innkeeper.'
Third declension.
Mare (sea) is 3rd declension.
'Tempus' is third declension.
First declension.
Third declension.
Consul, consulis is third declension.
Yes, declension is of a major importance
The Latin word caupo means "a petty tradesman". The commonest derivative of this in modern English is the word "cheap". Old English had the word ceapian, meaning "to trade", which represents an early borrowing of caupo into Germanic (German still has the word kaufen, "to buy", from the same source). The expression "god chep" in Middle English meant "a good bargain", and this led "cheap" to develop its modern sense of "inexpensive".
The Latin noun Homo, hominis is in the third declension.
Esse is the verb "to be". Only nouns are declined, therefore it is in no declension.