As with humans, chickens do sneeze –normally to clear the nasal passage.
If it is a regular thing then it could also signal a temporary cold.
Hens can suffer from colds during the wet and cold months, it’s not uncommon. Using Citricidal drops and Apple Cider Vinegar, added to their water, can be helpful in keeping the auto immune system healthy.
Keep an eye on them and if it persists or gets worse, the vet might be necessary.
If they have other symptoms like coughing, gasping for air, bubbly or mucousy eyes with a rattly chest then this could be Mycoplasma. Treatment for this is normally with antibiotics and a visit to your vet is recommended.
Birds suffering with respiratory disease should always be isolated from the other healthy hens, given lots of TLC and be given veterinary attention where necessary.