Singing is important because like all the other elements of Capoeira, it infuses energy in the game and as a whole, but it also maintains the vocal tradition of Capoeira. Without singing, the roda would lack energy, color and authenticity.
Portuguese is the traditional language of Capoeira and all its songs (or almost all its songs) are in Portuguese.
As opposed to Candomblé (originating directly from Africa) which has been developed by safeguarding the language of Yoruba, Capoeira chose Portuguese as the language, probably because it was originated from a mixture of ethnicities and the most practical way for the slaves and their descendents (from different origins) to communicate among each other would have been to adopt Portuguese as the language. The songs are the soul of Capoeira, of its history and of its tradition; when we translate these songs, their meaning, their strength, their melody and their identity are diminished. Portuguese is the universal language of Capoeira.
Each song has a meaning. During a roda, it is customary for the one leading the singing to make a connection with the game that is being played at the center. If the intention is not to influence the game, it is at least to talk about it. An easy example: “a bananeira caiu (the banana tree has fallen)” could be sung if someone has just fallen and especially while trying an acrobatic movement or if the person is usually stable as a column. Other songs can be used as warnings asking the Capoeiristas to play with more calm, slower or to pay attention because the opposing person may be a new player, or a more experienced one or an outsider to the group. There are many possibilities. When we begin to understand Portuguese, a new world of understanding opens up.