Meaning of the word "an old dog barks not in vain" in English

What does "an old dog barks not in vain" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

an old dog barks not in vain

US /æn oʊld dɔɡ bɑːrks nɑːt ɪn veɪn/
UK /ən əʊld dɒɡ bɑːks nɒt ɪn veɪn/
"an old dog barks not in vain" picture

Idiom

experienced people do not give advice or warnings without a good reason

Example:
Listen to your grandfather's warning; an old dog barks not in vain.
When the senior consultant raised concerns, I remembered that an old dog barks not in vain.