The relevant language courses to work as a nurse in Germany is A1 - B2. Let us explain: 

A1:  120 – 140 hours / ~2 months intensive training

Outcome: You can understand and use familiar everyday expressions and very basic phrases. You can introduce yourself and others and can ask and answer questions about personal details such as where you live, people you know and things you have. You can interact in a simple way provided the other person talks slowly and clearly and is prepared to help.

A2:  120 – 140 hours / ~2 months intensive training

Outcome: You can understand sentences and frequently used expressions: very basic personal and family information, shopping, local geography, employment... You can communicate and exchange information on familiar and routine matters. You can describe in simple terms aspects of your background and immediate environment.

B1:  140 – 180 hours / ~2.5 months intensive training

Outcome: You can understand the main points of clear standard input on familiar matters regularly encountered in work, school, leisure, etc. You can deal with most situations likely to arise whilst travelling. You can produce simple connected text on topics which are familiar or of personal interest. You can describe experiences and events, dreams, hopes & ambitions and briefly give reasons and explanations for opinions and plans.

B2:  140 – 180 hours / ~3 months intensive training

Outcome: You can understand the main ideas of complex text on both concrete and abstract topics, including technical discussions in your field of specialisation. You can interact with a degree of fluency and spontaneity that makes regular interaction with native speakers quite possible without strain for either party. You can produce clear, detailed text on a wide range of subjects and explain a viewpoint on a topical issue giving the advantages and disadvantages of various options.

It is important to reach this level of German, not only to pass the exam so that you can make it to Germany but also for you to feel comfortable and confident while interacting with your employer, colleagues and patients in Germany. The main component of your success in language learning is your own commitment.