The correct age to start solids is between 4 and 6 months, preferably closer to 6 months. Good starter solid foods are any steamed vegetable that is finely pureed - carrots, peas, potatoes, and apples.
You can give a variety of solid foods to your 5 month old kid, just make sure the food is soft to avoid choking. Examples are bananas, pears, saltine crackers, pasta, and yogurt.
Your kid could have any of the first stages of baby food or creal found in the grocery store. You could boil stuff like pumpkin, yam or potato as well.