Subject-Verb agreement is the how you conjugate the verb. Here is examples. the verb "to walk" would be conjugated like the following: "I walk" "You walk" "He/She/It walks" "We walk" "They walk" The subject is the fist part and the conjugation of the verb must agree with the subject you are using. So, I couldn't say "I walks to work everyday" because the conjugated form "walks" can only be used with the subject "He/She/It" I hope this helps! :)