Spack (1988, p. 42): '"the most crucial skill a student can possess is 'the complex activity to write from other texts', which is 'a major part of their academic experience'"'
When you use another person's words in your own writing, it is known as a direct quotation. These must always be cited properly and enclosed in quotation marks (MLA, APA, Chicago, etc).
To state something written or said in new words, particularly in a shorter and simpler form to make the content clearer, is known as paraphrasing (Cambridge Online Dictionary, 2022).