The second sentence, “He was only twenty-two,” is an example of direct characterization.
Direct characterization means that the author is explicitly given the reader information about the character. Here, the author is providing the character's age.
The first and the last sentences, “He looked thin and very serious,” and “He needed a new overcoat and he was without gloves,” are examples of indirect characterization.
Through this sentences we can infer that the character is poor, since he looks "thin" and is in need of new winter clothes, and that he has suffered, since he has a serious look.