-s
The form -es is also used. The suffix -s is pronounced [PH:-][PH:s] after the consonant sounds [PH:p][PH:,] [PH:t][PH:,] [PH:k][PH:,] [PH:f] or [PH:T]. After other sounds -s is pronounced [PH:-][PH:z]. The suffix -es is pronounced [PH:-][PH:z] after vowel sounds, and [PH:-][PH:I][PH:z] after consonant sounds.
1 suffix -s or -es is added to a noun to form a plural.
...her two beloved cats.
2 suffix -s or -es is added to a verb to form the third person singular, present tense.
He never thinks about it...