Sources with direct knowledge tell TMZ ... when Shaq and Haliey Welch linked up in Nashville last weekend, the NBA legend started dropping knowledge.

We're told Shaq gave Haliey a bunch of tips on how to deal with fame ... advising her to keep a smart team around because folks will come out of the woodwork to try and take advantage of her.

Our sources say the conversation included Hailey showing Shaq some of the hateful comments she's getting in response to her viral video ... with Shaq telling her to pay the haters no mind because none of them actually know her.

As we reported ... Shaq and Haliey partied at Jon Bon Jovi's new joint in Music City the night after she was pulled onstage at Zach Bryan's show in Nashville.

After Shaq saw Haliey with Zach, our sources say he told his team he wanted them to get in touch with her so she could make an appearance at his DJ gig at Bon Jovi's place ... and that's how the meeting went down.

Shaq and Haliey, we're told, ended up chopping it up for about an hour ... and after their convo, Hailey considers Shaq a friend and someone who truly cares about her.

It wasn't all talk ... Shaq also brought Haliey up to the DJ booth during his set, and when she came out, the crowd erupted. Remember, she knows how to have a good time. 😜

While Shaq's helping Haliey navigate fame, it sounds like he didn't school her on navigating the DJ booth ... because at one point he ended up stepping on her foot!!!