Move and Attack is a basic, activated ability with the following text: Tap -> This unit may take one step. Then, it may attack.
Normally the unit's movement path is one step between two adjacent surface locations, but some abilities may modify this, including Movement +X, Moves Freely, Burrowing, Submerge, Airborne, and Voidwalk (and effects like Felbog Frog Men). See the entry for Movement Path for more information about declaring paths.
The Move and Attack ability does not use the word 'target,' so you do not declare any targets in advance. As it resolves from the storyline, you declare your full movement path, then resolve that movement. After completing all the movement (if any), you may attack, declaring your attack target at that time. See the 'attack' codex entry for further details on the attack sequence.