Mineral acids are non-organic acids. Sulfuric, nitric, hydrochloric, and phosphoric acids are probably the most important commercially, though they're certainly not the only mineral acids.
"Concentrated" generally means "the standard purity supplied by manufacturers." This varies quite a bit depending on the exact acid; it can be nearly pure (sulfuric or nitric acids), somewhat less so (phosphoric acid, typically about 70%), or quite a bit less (hydrochloric acid at around 38% or so).