To be watching for something or someone. Be on the lookout for my email! It will have all the instructions you need for the project.A: "What are you guys doing?" B: "We're on the lookout for Mom's car, so we can tell Dad to stop working on her surprise gift when she gets here."
be on the look out
and BOLO
phr. & comp. abb. establish and maintain surveillance [for someone]. (A police notation.) BOLO for a 65-year-old woman with tattoos on her upper arms. We’ll be on the look out for your stolen car.