Answer:
It will expand because the helium atoms will move more quickly and get farther apart.
Step-by-step explanation:
When a gas absorbs heat, the internal energy of its molecules increases, the gas intend to expand because, with more energy, the molecules will move quickly and will get farther apart.
If the container is not flexible, it will contain the molecules, and the gas pressure will increase, but if it's flexible, it will permit the gas to expand and will expand too.