"Attack" is a wine tasting term.
After you put wine in your mouth, it spreads around your tongue, roof of the mouth, and then as you swallow it, it travels down your esophagus and into your stomach. The "attack" is the first impression you get from this entire process.
Also, the impression you get when you swallow a wine and afterwards is called the "finish," and the impression you get between the "attack" and "finish" is sometimes called the "mid-palate."
Comments describing an attack can be either "strength (quantity)" or "quality." When describing strength, you would say something like "strong" or "weak (light)."
In addition, qualitative comments can be expressed as "gentle" or "smooth." For example, if you say "New Zealand Sauvignon Blanc has a sour taste on the attack," it means that you can feel the sourness the moment you put it in your mouth.
