Development
Development is bringing pieces off the back rank to squares where they control the center and can join the fight.
Knights and bishops should leave the first rank before you start pawn hunts. Castling counts as development for the king and the rook. A lead in development means your pieces are already working while the opponent is still untangling.
White has a knight on f3 and a bishop on c4. Black still has both bishops and the kingside knight at home. The next jobs for Black are …Nf6 or …Bc5, not a third pawn move.
The coach treats a minor piece leaving the back rank as development. If you keep shuffling pawns while Maia brings pieces out, the tactics in this glossary start to appear against you.