Sporting director Ross Wilson said Cá had an "exciting profile" who had shown "real growth" over the past couple of years.
"We're committed to adding talented young players who can grow with us," he added. "We're excited to work with him in our development programme."
Cá, who is expected to link up with Newcastle United's under-21 squad this season, was drawn to the club by its ambitions on and off the pitch.
"The project here, the lifestyle, and the club's ambition made this the right move for me," he said. "I'm a forward who likes to find space, link play and work hard for the team. Scoring goals is a big part of my game, but my focus is always on contributing to the group, whatever helps the team win."
The forward, who academy director Steve Harper said had enjoyed "valuable" spells in Portugal and Spain, believes his direct playing style will translate well to English football.
"Here in England, it's a direct and fast style - maybe in one or two touches, you are already in the opposition box. In Spain, similar to Portugal, it's maybe a more horizontal game. But I like this type of direct play. At Newcastle, I know it is a style that fits the way I play - the players are not only scoring but also fighting for the club, and it's a way of playing that is familiar to me and I like."
Cá joined Levante from Portuguese club Amora last summer and scored four goals in 27 appearances for the Spanish side's under-19 team in his only season there. He had made his senior debut for Amora in the Campeonato de Portugal during the 2024-25 campaign, following a standout youth campaign the year before in which he scored 13 goals in 31 appearances.
Reflecting on his reception since signing, Cá said he had already been made to feel at home on Tyneside.
"I know it's going to be a really different experience for me. It's a new chapter in my life and I'm very eager to start it here at Newcastle United. Aside from being a historic club in the Premier League, in recent years it's a club that has played in the Champions League and won the Carabao Cup. I like the fact that everyone has come up to me to introduce themselves and say, 'hi Afner' - they know my name, they know who I am, and everyone has been very friendly."