The basics on speech and language disorders from the CDC:

https://www.cdc.gov/ncbddd/childdevelopment/language-disorders.html

Birth to 5: Watch Me Thrive! Keep an eye out for these early childhood milestones…

https://www.acf.hhs.gov/ecd/child-health-development/watch-me-thrive/families

Great activities to stimulate speech and language development in your little one!

https://www.asha.org/public/speech/development/Parent-Stim-Activities.htm

A go-to resource for typical speech and language development:

https://www.asha.org/public/speech/development/