盗難を防ぎましょう

Here's a sign I saw in the bicycle parking area around one of my work places.

ご注意（ちゅうい）- Attention
鍵 （かぎ）- Key
は- Subject marker particle
必ず（かならず）- Always/Certainly/Be sure to
ツーロック - A key lock; Usually stays in lock when open and is removed when locked.
して- Do in the -て form
下さい（ください）- Please

Translation: Please be sure to remove the key from the lock.

自転車（じてんしゃ）- Bicycle
バイク- Motorbike
の- Possessive Particle
盗難（とうなん）- Theft/Robbery/Stolen 
を- Particle that links the noun to the verb
防ぎましょう（ふせぎましょ）- Protect/Guard/Prevent 

Translation: Protect your bicycle/motorbike from theft. 


これ以上です。

ジョシュア