You can read a helpful explanation of what constitutes plagiarism provided by the Plagirism.org web site, or take a 25-minute tutorial "How to Recognize Plagiarism" from Indiana University Bloomington.
Here's a short (10-item) quiz. If you are taking the short quiz, keep track of how many incorrect responses you have as you go along. The web site also offers a longer certification test, but you must register to take it.
Purdue's Online Writing Lab (OWL) has a web page that explains Quoting, Paraphrasing, and Summarizing.
Cite all sources quoted or paraphrased in a research paper. For rules and examples of APA Style, consult the Publication Manual of the American Psychological Association, 7th ed. 2020 (copy available at Andersen Library's Reference Desk).
Online citation formatters and citation help from library databases are not foolproof. Always review your citations to be sure they are correct.
The American Political Science Association has a style manual:
Publication Manual of the American Psychological Association