I have understood that the Carthaginian army during the Punic wars was composed of people from different nationalities and languages, example: Numidians, Iberians, Gauls etc. So how did Hannibal command his troops? I imagine they met before battle with his high ranking officers that were probably from Carthage and then the troops just had to follow them. right? How would that work?
To put it simply: Punic and Greek.
The first applies due to the long history that the Carthaginians already possessed with the various Phoenician cities along the North African coast, the close cultural and material ties with the Libyco-Berber peoples and the co-dependency that they had established with the Numidians in the following centuries. The traditional narrative for Iberia states that around 537 BCE, Hamilcar Barca himself conquered a swathe of south-western Iberia but Phoenicia presence in the area probably outdated him by 2-3 centuries. Tribes like the Turdetani have left Punic inscriptions in the archaeological remains of their towns lending credence to this phenomenon.
Greek is a bit more of an extrapolation on my part but it’s very plausible. Greek colonies like Massalia and Emporion stretched their influence into both the Gallic and Iberian hinterlands, Punic and Greek relations stretched as far back as the 8th century BCE and Hannibal’s own tutor was the renowned Sosylus of Lacadaemon who taught Hannibal Greek, thus it’s likely he was able to communicate with the Tectosages, Volcae and Helvii he recruited from during his march through Gaul (and their captains in turn probably would have acted as translators with the Allobriges and Insubres).
Sources
A Companion to the Punic Wars by Dexter Hoyos (2011) Colonial encounters in ancient Iberia: Phoenician, Greek, and indigenous relations by Michael Dietler and Carolina Lopez-Ruiz (2009)