The photographic effect of parts of a scene appearing out of focus in a captured photograph. It is often used to "blur" the background in a portrait.
Bokeh is an optical effect that looks distinct from blur to a trained eye.
In traditional photography, a significant bokeh effect requires a physically large-diameter lens, as compared to a phone camera lens. Phones with larger lenses and sensors can produce a very limited bokeh effect.
Some phones can simulate bokeh using software. Some merely blur the background, while better software produces something closer to bokeh. Some phones use multiple physical camera sensors to provide additional information that can improve the bokeh effect considerably.