Stress can have a noticeable effect on learning mainly on memory. It could be both effect positive or negative.
Let start with positive effect , it can improve attention and consideration alertness and thus help with memory formation. But too much stress can diminishe our cognitive function by negatively impacting our brain's ability to retrieve information also update existing information.
Recalling of information is critical during exams, it also important when we need to recall and put it to use .
Our brain's ability to update any existing information is important when learning complex concepts.
So, self care and and stress management help our brain to learn.