"This is a Wehrmacht soldier armed with a K98. The backbone of the german army; most of them are hardened veterans from the Eastern Front."— Official game quote
The Wehrmacht is the name of the German Army's backbone, their version of your regulars. Although these troops were powerful in real life, in MnB they are mostly cannon fodder. Most of these guys are from the Eastern front (Russia), and are worthless except for their meatshield value. They are armed with the standard bolt action rifle the Germans used (the K98). They usually are dealt with easily in later waves, when your AI systems are developed, but in earlier waves when you have only a few soldiers, they can be dangerous due to their accuracy. They take a long time to aim, but their accuracy can almost ensure that they will land a hit on one of your units. These guys also have their own blitz wave, which may pose a problem if not taken out rapidly.
The Germans' military strength was managed through mission-based tactics (rather than order-based tactics) and an almost proverbial discipline. In public opinion, the German Army was, and sometimes still is, seen as a high-tech army. However, such advanced equipment, while featured much in propaganda, was often only available in small numbers or late in the war, as overall supplies of raw materials and armaments ran low. For example, only 40% of all units were motorized, baggage trains often relied on horse-drawn trailers and many soldiers went by foot or used bicycles (Radfahrtruppen). In real life they had access to the MP-40 and grenades. The word Wehrmacht actually referred the entire German military, whereas the Heer referred to the land component of the Army.