A citation is when you specify the person(s) that have helped inform you on a specific topic.
For example, when you use quotations within your work, you will specify the author, date and page that this quotation came from.
e.g. (Silverman, 2018:89)
If you have paraphrased (put something in your own words) you do not need to specify a page.
e.g. (Silverman, 2018)
An in-text citation is when you might mention the author within your sentence. In this instance, you will place the place the date and page within brackets.
e.g. Silverman (2018:89) suggests that "..."