Five-month old babies are still very young (so they're digestive systems still need milder fooder). Also, although babies get their teeth at different ages, a good number of five-month old babies either have no teeth or only have one or two.
Babies that age usually get a large part of their nutrition from milk (breast or formula). Other foods (besides milk) many babies that age eat are infant cereal and strained, commercially prepared, baby food. Some mothers make their own baby food rather than buy commercial, strained, baby food.
A common menu for a baby (in addition to whatever milk s/he gets) might be something like this:
Baby cereal (with milk) and strained fruit (maybe applesauce, peaches, or pears) for breakfast. Babies that age don't need much cereal. Enough cereal to, maybe, cover the bottom of a small cereal bowl (and just a little more than that) is about what they may eat.
A common lunch for a baby that age might be a half jar of a strained vegetable (like sweet potato or peas, for example) and a half jar of strained fruit. The baby may not eat the entire half-jar, so a half jar at lunch and keeping what's left in jar for dinner works well. A half-jar of strained after the vegetables is something a lot of babies may have.
Another possibility for lunch might be cereal and fruit (again).
It's common for bottle-fed babies to be offered formula after each milk.
With each new food that's introduced a baby may have a reaction, so it's good to introduce new foods one at a time in order to be able to know which food seems to produce the reaction.
Keeping variety of foods to a minimum helps prevent the child from developing food allergies, so sticking with a limited diet (maybe one that offers a green vegetable at one meal and an orange vegetable at another meal in any one day) is what a lot of mothers do.
Because babies eat so little, and because they have important nutritional needs, it's important that they get plenty of milk or formula to ensure they get their nutritional needs met. Even if they have a little food for three meals it's not a time to think about eliminating too many milk feedings. Eliminating formula feedings usually comes much later when the baby is eating more than s/he eats at five months old.