They can eat meals just like we do on Earth.
At the beginning of the 1960's, space food was bite-sized or placed in aluminum tubes. The food was prepared this way so that they wouldn't be too heavy or take up too much space. From the 1970's, during the Apollo period, the number of space food items began to increase. Currently, there are about 150 different types of food. The meals are very similar to the meals we eat on Earth.
Space foods are in plastic containers. Some space foods can resume their consistency by adding cold or hot water, while others can be heated up in the oven. Foods such as fruits, bread and nuts can be eaten just as they are. When drinking liquids, a straw is used to suck the liquid out of a sealed package. This is done so that it will not spill or possibly cause any damage to machines.
At the International Space Station, 300 different types of food are planned to be on the menu.