A set of pronouns that gender-non conforming (non-binary, transgender, etc) people may use. The two pronouns may be used interchangeably, or they may have a preferred one.
In this case, they prefer the pronouns he/him but do not hate the pronouns they/them.
He/they gave me his/their spotify playlist! He/they has/have an amazing taste in music!
I love his art. He draws very well!
They chose just the right colors, their taste in art is amazing!
His cat is named "Cookie", they must love cookies!
Same as assume, except with a reason.
I presume Dasha is going to choose her elective as performing because she loves theater.