。
She gets along very well with her students.
Literal
She [topic-は] students [with-との] relationship [subject-が] very-well is-going.
~との関係 means 'relationship with' — と marks the other party, の makes it possessive, and 関係 means 'relationship.' うまくいっている means 'is going well' — うまく (skillfully/well) + いく (to go) in the progressive form. 生徒達 (せいとたち) means 'students' with the plural suffix 達.