There's a girl in our class who is pretty but has a very stern look about her. She looks a little scary actually.
There's a girl in our class who is beautiful but I hesitate to talk to her because she doesn't look very friendly.
1) There's a girl in our class who is pretty but has a very stern look about her. She looks a little scary actually.
「クラスに綺麗な女の子がいるんだけど、きつい顔してるからちょっと怖いんだよね。」
stern で「いかめしい・険しい」
2) There's a girl in our class who is beautiful but I hesitate to talk to her because she doesn't look very friendly.
「クラスに綺麗な女の子がいるんだけど、あまりフレンドリーな感じじゃないから話しかけるのをためらっちゃうんだよね。」
hesitate to talk to 人 で「人に話しかけるのを躊躇する」
ご参考になれば幸いです!