Many companies use recruiting management software to screen candidates for job openings. Instead of a person reviewing your resume, the software screens resumes based on the terms included the resume. Resume keywords are the words that those hiring managers search for when going through their database of resumes. In order to get found, your resume needs to contain keywords that directly target the jobs you are interested in.
The keywords in your resume should reference specific job requirements, including your skills, software and technology competencies, relevant credentials, and previous employers.
Here's more on resume keywords and how to use them to ensure that your resume stands out from the crowd and you're flagged as compatible with open positions. Also check out hard skills vs. soft skills, you'll need to include both on your resume.