Obviously. A cow is a mature female bovine that has given birth to at least one or two calves. Therefore it should be "assumed" (in you, the asker's, case) that indeed, cows do have a "birth canal" or, more properly, a vagina.
Then that calf (and the cow) is in a lot of trouble, and you need to assist that cow right away. The calf needs to be pushed back in in order to get the other leg into the birth canal. The head is...
You could, but you would have to do a search on search sites like Google, Yahoo, Dogpile, Ask.com, etc. to find pictures of a cow giving birth. But I will save you the efforts of looking for images...
Cows give birth any age, since a cow is a female bovine that has already had a calf or two. Heifers, on the other hand, give birth when they're ~24 months of age. Since the gestation period is around...
If the calf is alive and healthy, then just leave momma and her baby be for a few hours to let the cow mother-up to her calf. If the calf doesn't appear to have gotten up and suckled from Mom yet,...