Bellingham produced a midfield masterclass in Tuesday's 3-1 friendly win in Glasgow, becoming the first England player to both score and assist in a game against the Scots since Kevin Keegan in May 1979.
The display continued his outstanding start to the campaign which has seen him score five times in four appearances for new club Real Madrid, where he has been playing as the most advanced of four midfielders.
“He’s obviously playing a slightly different role [for Real] and he’s got a lot of freedom there because he’s got three really athletic midfield players behind him," the England manager said.
“So for most of the season they’ve been playing without a nine, so he’s been the one making [runs into] the box.
“He’s still somebody we’re talking to a lot, trying to help him with his game because he’s still got areas to improve. But [on Tuesday] he was terrific.
“The biggest thing for me is his personality. We knew our anthem would be booed, we talked to the players about taking energy from that. We wanted to prepare them for everything for the game.
“But I’m looking at him stood in the line and I know what’s coming. That’s the sort of thing that makes the difference, the mentality of the player.
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“He’s definitely got leadership qualities. The great thing in this group is our senior players are such good leaders, we’ve got six or seven who are incredible.
“The two full-backs who played Tuesday night [Kyle Walker and Kieran Trippier] are incredible characters for us, real unsung heroes, and they set a brilliant leadership example around the place. Where he’s bright enough is to attach himself to those sorts of characters.
“The people you mix, the people you hang around with in life, probably are a good indicator of where you’re going to end up. He’s really savvy at that. I think his whole life and how his family have looked after him have given him a great start but there’s still a lot to go.
“That’s for all of us to make sure we’re helping him in the right way, pushing him at the right times, helping him with the bits of his game that can get better, but also allowing him to flourish as he has on Tuesday.”
Bellingham left boyhood club Birmingham for Borussia Dortmund in 2020 before joining Real in a deal worth at least £88.5million in the summer.
Southgate believes playing overseas will only help Bellingham's development but played down the risk of 'burnout' for a player who made his first-team debut aged 16.
“In Dortmund he used to have a winter break for a start," Southgate said.
“That would help our league, there’s no question of that. I think Spain may have the same. I think the biggest thing is he’ll be opened to different life experiences that are going to help his game. You can work with world class players in some English clubs but the club he’s at the expectation, it’s the biggest club in the world. He will be learning from some outstanding players. Playing against different tactical systems, different sorts of problems.
“I’m not sure I’ve come across a player that’s burnt out,” Southgate added. “There might be different reasons for players not fulfilling their potential.
“But I think burnout is a careful word. Psychologically some players maybe reach a level where they feel they’ve done enough, they’ve had enough. I’d have to sit for a while and think about that.”