A terminological note: nouns, adjectives and pronouns have declensions; verbs have conjugations.
If you have the infinitive (second principal part) and length markings on your vowels, the task is easy:
1st conjugation: infinitive ends in -Äre(passive/deponent -ÄrÄ«)
2nd conjugation: infinitive ends in -ēre(passive/deponent -ērī)
3rd conjugation: infinitive ends in -ere(passive/deponent -Ä«)
4th conjugation: infinitive ends in -īre(passive/deponent -īrī)
If you have the infinitive but no length markings, you can tell the 2nd and 3rd conjugations apart by looking at the first-person singular indicative (the first principal part). If this ends in -eo, it's a 2nd-declension verb; if it ends in -io, (e.g., capio) or just -o (e.g., cano) it's 3rd.
If you don't have the infinitive, knowing one or more forms from the present indicative can help:
1st conjugation: first person singular ends in -Å, third singular in -at
2nd conjugation: first person singular ends in -eÅ, third singular in -et
3rd conjugation: first person singular ends in -Å or -iÅ, third singular in -it
4th conjugation: first person singular ends in -iÅ, third singular in -it
In the absence of the infinitive, -iŠverbs of the 3rd conjugation can be hard to tell from 4th-conjugation verbs. Having vowel markings can help; for example, 4th-declension venīmus"we come" (long ī, accent on the second syllable) versus 3rd-declension capimus "we take" (short i, accent on the first syllable). The imperatives also differ: 4th-declension venī "come!" versus 3rd-declension cape "take!"
Esse is the verb "to be". Only nouns are declined, therefore it is in no declension.
You can tell what declension a Latin noun is by looking at the noun's genitive singular form.
Third declension.
First declension.
'Tempus' is third declension.
The Latin noun Homo, hominis is in the third declension.
Third declension.
Latin has no such word. There is a first declension verb intento, which means "I point at, point (weapons etc) in a threatening manner, or threaten".
Consul, consulis is third declension.
According to an online Latin to English Translator, clamat means cries.
The Latin word cīvitās in the nominative case, cīvitātis in the genitive, is a third declension feminine noun.
WARD in Latin is Defendo in first declension. fendere in second declension. fendi in third, and fensum in fourth.