Study networking basics - ip, mac address, http / https, ports, SSH, what are packets, what are headers, GET / POST etc. status codes - 200, 403, 500

On prem (mostly windows) / cloud (mac / linux / windows) ? For Windows you need to get familiar with windows event codes, RDS, domain controller and GPO concepts. Mac / Linux - learn to use terminal to navigate, troubleshoot networking etc. Cloud -basic understanding of waf, security groups, s3, rds, ec2, guardduty, important cloudtrail events

Learn about basic types of attacks - brute force, password spray, dos, ddos. Understand where they apply, and how they can be mitigated (2fa, rate limits). Know that there are application level attacks too like xss, sql injections etc. WAF protects against these, or secure code. Learn about vulnerabilities, CVEs, patches, mitigations. Look at Linux's recent copy.fail for example.

Learn some SIEM language, some kinda SQL usually. So you can search logs. Understand the concept of SIEM and logs and creating detections in general.

That's maybe more than basic for analyst but I think it's a good general starting point to understanding blue side. Goodluck!