。
Wooden buildings catch fire easily.
Literal
Wooden-construction-building [topic-は] fire [subject-が] attach-easy.
~やすい ('easy to X') attaches to a verb stem to form an i-adjective meaning 'easy to do' or 'prone to X.' The opposite is ~にくい ('hard to X, resistant to X'). Note the intransitive 火がつく ('fire attaches/lights') — fire is the subject and the burning happens by itself, rather than someone setting it.