Bison are herbivores, so they really don't want to eat you. If you get too close or threaten them, an irate adult might charge you, or maybe just bluff charge. So, if you keep a reasonable distance and move laterally, they don't care much. Once in a while you will find a bison cow who is overly protective of her calf, or maybe find a bison bull who is in a bad mood, so allow a safer distance and everything is OK. It is possible to get gored by a bison if you were stupid.
I was in Yellowstone, walking at night about 45 minutes after sunset. I had my headlamp switched off as I ambled along a trail. All of a sudden, there was a Snort just a few feet in front of me. I lit up a light feature on my camera and saw that it was a bison bull. I just backed up and then moved laterally until I was safe, then ran like crazy!