This isn't plagiarism. The student has undertood the source and put the relevant information into his or her own words. This shows that the student has understood the text and is able to explain the information relevant to the essay.
Smile: Plagiarism is adapted from by Don't Cheat Yourself, University of Leicester and is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Based on a work at https://www2.le.ac.uk/offices/ld/resources/study/plagiarism-tutorial. Image : Josh - People vector created by Vectorpocket - Freepik.com Image : Background vector created by Vectorpocket - Freepik.com