Summer job

Although there is a shortage of labour in the low-paid service sector (incl. waiters), your job chances obviously depend mostly on whether you can understand and converse with customers. A1 night not be enough for this, so keep your options open also for related jobs that do not require language, like washing dishes.
You also did not mention your visa status. If you are not EU citizen or have a work permit already, your chances might be slim.

Thanks for your reply! I am EU citizen

As an EU citizen, a Lithuanian should be eligible to work. And there can also be jobs in food service preparing food or cleaning etc. where one would not have to interact much with customers. But of course the better one's German the more chances one has.

The question I would pose is what is one's purpose? Many assume Germany is a rich country compared to some others so they will be able to save lots of money. But living expenses are also high. If seen as an opportunity to improve one's German and to get to know the country it might be worth it but hoping to save money on a min. wage job is an illusion. The question is if one can even manage to pay their rent and food.

Some foreigners come to Germany and say work in the agricultural sector and even manage to save something to take home. But this is often dependent on having a cheap accommodation provided – which is often on a very low standard.