The word is kibitzer, pronounced \KIB-it-ser\. It is a noun. It is defined as
A giver of uninvited or unwanted advice.
Used in a sentence: The Enemy can influence many a kibitzer in our daily lives to off-track us from trusting in God, yet we must continue to increase our faith in Christ, especially in the midst of negative influences.
Proverbs ch.3: v.5-6