Her name was Linda, and she was a year younger than Tony.
Literal
Name [topic-は] Linda [copula-で], Tony [than-より] 1 year-younger [polite-でした].
で is the te-form of the copula だ/です, used to chain predicates: '[name] is Linda AND [person] is younger.' より is the comparative particle — 'X より Y' = 'Y compared to X.' ~歳下 ('X years younger') uses 年 or 歳 with 下 ('below, lower').