The pair played together at Lille.
“It lifts everybody to see players of this quality coming in and helps the team a lot," Gana told evertonfc.com.
“We want these types of players to help us achieve what we want this season. We are determined to improve on last year and the manager is strengthening the squad.
“I was excited as soon as I heard Lucas might be coming to Everton.
“I know him very well from our time at Lille. He is a good young player and, hopefully, he will show what he can do in our team.
“He is a really strong left-back – his standout feature is the quality of his defending. It is tough to dribble past him. He is very good at one-on-one defending.
“He can go forward and be dangerous in attack but he gets back quickly. And his crossing is excellent."