have one's heart set on是idiom，一门心思，渴望，倾心于。
= to want something very much, so that you would be very disappointed if you do not get it
set v. 放，置；使处于（指定的地方、位置）。
= to put something in a particular place or position

【例句】
She's got her heart set on ballet lessons.
她一心想上芭蕾舞课。

Our house is set back from the road.
我们的房子离公路有一定的距离。