在家 (pinyin: zài jiā, written "zai jia" or "zaijia") means to be at home. Below: its meaning, pronunciation, stroke order, and example sentences, so you can learn how to read, say, and write 在家.
Meaning
to be at home
(at a workplace) to be in (as opposed to being away on official business 出差[chu1 chai1])
(Buddhism etc) to remain a layman (as opposed to becoming a monk or a nun 出家[chu1 jia1])