The authors agree that the surname derives from a name of medieval Germanic origin. A. Bongioanni links it to the Lombard name Wala, documented as early as a Farfa text of the year 761, and notes that its meaning is equivalent to that of the terms wälsch and welsch, that is, "outsider" or foreigner. E. Rossoni broadens this perspective: he proposes that the surname could derive from the medieval Germanic name Walhari, compounded from wal ("strange, foreign") and hari ("army"), although he considers an origin in the Lombard Guala, from the term wahhal ("watchful, awake"), more likely.

As for geographical distribution, Rossoni places Guala as a typically Piedmontese form, found in Acqui Terme, Cassinelle, the Alessandria area, Turin, Vercelli and Biella, with an extension to Genoa. He also records variants such as Gualla, present in the Pavia area and in Piacenza; Gualazzi, possibly originating in the area between Piacenza and Cremona; Gualina, from the Brescia area; and Guallina, located in Melegnano. Bongioanni, for his part, mentions as related surnames in Piedmont and Lombardy the forms Valla, Valotti, Galotti, Gallio, Gualino and Vallino, and in Friuli-Venezia Giulia the variants Vale, Valussi and Galliussi, with the patronymic Gualenghi.