What does the traffic sign yellow triangle with two arrows up and down mean?

Traffic signs A yellow triangle with two arrows up and down is a two-way traffic sign and is a warning sign, as shown below:

Two-way traffic signs are used to remind vehicle drivers to pay attention to meeting vehicles. It is located on a road section that is separated from two-way traffic and temporarily or permanently does not separate two-way traffic for some reason, or is located at an appropriate location before a road section from one-way traffic to two-way traffic.