Even if you have already read about a piece of grammar a number of times, such as present perfect, if you struggle with it, there is no shame in returning to explanations in your first language. Many students, and teachers as well, perceive the first language as a crutch, rather than an asset. If the concept is very confusing, or is very difficult for that particular student, then they need all the help they can get.
Often students think that because they have already learnt something before, then they must read about it only in English otherwise they won't feel like they are improving. It is possible to read every word in the explanation, and look up each unknown word, and not understand the underlying grammatical meaning. That's why it is important to be realistic and leave the ego at the door. It is better to go back to the explanation in your first language first and get the information quickly and clearly, and then look at the example sentences. If it takes 5 minutes to read it in your first language, and 30 minutes to read it in English, then it would be much more efficient to read it in your first language again.