The Universal Galactic Language (UGL) is a intergalactic communications system provided to commanders by the Federation. It is a language standard based on a set of 16 signals that enable communication across human languages and between known sentient beings across the known galaxy sectors. The set of signals is dependent on your mission type.
Commanders may use up to four of the signals to communicate with those in close proximity. The limit of four was chosen by the Federation in order to hinder the potential to overload/abuse the communications module. Although at first glance the number of signals may seem limited, one can produce a grand total of 1820+560+120+16=2516 different messages (calculation) with this language.
The signals are carefully chosen so as to minimize unnecessary misunderstandings that may lead to armed conflicts such as the Thousand Years' War of Irgon-9, in which a fleet of pilots intending to seek supplies from a neutral station broadcasted the non-UGL message "Ktoh-al-shmar" in species E-5931 dialect (which in some human colonies roughly translates to the colloquial greeting " 'sup my dudes"). This turned out to be a disastrous mistake -- the base was in fact inhabited by sentient species E-5921 (not E-5931), for which the message in Universal Galactic Language translates to "you no gg", an aggregate of all possible insults there could ever be in the entire universe. The fleet was shortly after overwhelmed by missiles, destroyed, and their cargo scavenged by the species, breaking at least 142 intergalactic peace treaties and trade agreements and unleashing several cycles of interstellar warfare. After resolution of the conflict and reinstatement of order by the Federation, the Universal Galactic Language is strictly regulated.