This a very broad question. There are many characteristics of the Beowulf that one can point to. In light of this I will mention only two. First, Beowulf has a strong emphasis on the heroic code. Bravery, courage, prowess in battle, and most of all victory is prized. It is one of the central features of the work. Beowulf epitomizes these qualities. He is sure of himself, fights alone and defeat all his foes. In the end, he even dies while he defeats the dragon.
Another quality that is found in Beowulf, which might be odd, is Christian theology. For example, Grendel is from the line of Cain, the one in the Bible who slew his brother. In this way, we see the genealogy of Grendel traced back to biblical times.
From these two points, we can tell that the work was produced in a culture where valor and Christianity were prized. Hence, we can posit that there was a mixing of cultures - Germanic, Roman, and Christian.