ménkǒu xiězhe “xiāofáng tōngdào, qǐng wù zhànyòng”, jiùshì yào yīzhí bǎochí tōngchàng

门口写着“消防通道，请勿占用”，就是要一直保持通畅。

The door says 'Fire lane, do not block,' meaning it must always be kept clear.