the snailEscargot means “snail”; l' is the contraction of le (“the”) before a vowel. In ordinary French, the noun is usually lowercase: l'escargot. The capitalization in l'Escargot may be used as a nickname, title, or proper name.
FR: On l'appelait « l'Escargot » parce qu'il avançait très lentement.
EN: They called him “the Snail” because he moved very slowly.