、。
If you work hard, your dream of becoming a baseball player will come true.
Literal
Baseball-player [to-に] want-to-become [quoted-という] you [gen-の] dream [topic-は], whole-life-hard effort-do-[cond-ば] come-true [probably-でしょう].
Complex relative structure: 野球選手になりたいというあなたの夢 — 'your dream, (called/of) wanting to become a baseball player.' ~という wraps the quote (direct desire ~たい) as a modifier of 夢. 一生懸命 ('with one's whole life and all one's effort') is a common four-character compound expressing dedication. ~ば conditional + でしょう for the probabilistic consequence.