This is the 2384th most frequent Spanish word.
bajo
Low; short; under; base.
In this sentence, 'bajo' is used as a preposition meaning 'under', indicating the position of the cat relative to the table.
El gato está bajo la mesa.
The cat is under the table.
Here, 'baja' is used as an adjective in its feminine form to describe the low condition of the temperature.
La temperatura está muy baja hoy.
The temperature is very low today.
Here, 'bajo' is used as a preposition indicating a condition or guidance under which something occurred, specifically under someone's supervision.