Tā yí ge rén qù le guówài dúshū, shénme shì dōu děi zìjǐ chǔlǐ.
She went abroad to study on her own and had to deal with everything herself.
Tips
usage
Literally 'one person'. Before a verb it means 'alone, by oneself': 一个人吃饭 'to eat alone'. It is the most casual word for this; 独自 is more neutral and 孤身一人 literary. As a plain count, 一个人也没来 means 'not a single person came'.
mistakes
个 is toneless here, and 一 takes a second tone before it because 个 is fourth tone underneath.