For a baby it is best to exclusively breastfeed for the first six months. This means only feeding breast milk to the baby and a supplement of vitamin D to your baby, recommended by your health practitioner.
At 6 months of age it is time to introduce the baby to solid food, since the baby´s iron stores begin to empty (a baby’s iron stores from his or her mother lasts for approximately 6 months). It is best to begin with mono-meals, like banana purees, vegetable purees and iron-enriched porridge (made by mixing with mother’s milk if possible).
Please see more about this in this article, “From Breastfeeding to Solid Food”.