Weave area. This sign is used to warn that you will be merging with another roadway as some traffic is exiting and crossing your path. In most cases, it is installed at highway interchanges that don't have dedicated merge and exit lanes, where traffic entering the highway may intersect with traffic exiting the highway. In most situations, traffic exiting the highway through a weave lane has the right of way over traffic entering the highway.
The weave area road sign is not used across the whole country and you may not see it in some states.