In most English-speaking countries, "Alandra" could simply be considered a contraction of "Alexandra", a feminine form of "Alexander" ("helper or defender of mankind").
However, you asked for the significance of this name in Spanish-speaking countries. There, the name "Alandra" means "lark". This is a variation of the more commonly known Spanish name "Alondra" (also meaning "lark"), which was originally a corruption of the name of a species of lark called the "Calandra lark". All of these names for the lark have their roots in the original Latin word for "lark", which is "alauda".