The Portugal attacker was speaking ahead of Milan's preseason friendly in Australia against Perth Glory.
Leao said: "We have an experienced coach who has already won here at Milan. We're a young group, with some more experienced players who have been here for a while.
"We're building the team, with the right spirit that helps even when we don't play well. Compared to the past, everything has changed. I feel that this year Milan will be a team.
"We have important players who can make the difference, but above all, there will be great team spirit."
On the prospect of Milan facing Como in a Serie A tie in Perth this season, Leao added: "It's not official yet, and I can't say much, but if we played here again, it would be really nice because we'd have a lot of fans, and that would be great."