This is the 10436th most frequent Spanish word.
construyendo
"Construyendo" means "building" or "constructing" in English.
In this sentence, "construyendo" is the present participle of the verb "construir" and is used with the verb "estar" in its present form to form the present continuous tense, indicating an ongoing action.
Estoy construyendo una casa nueva.
I am building a new house.
Here, "construyendo" is also the present participle and is paired with the imperfect tense of "estar" to indicate an ongoing action that was happening in the past, fitting the past continuous tense.
Ellos estaban construyendo un puente grande en el río.
They were building a large bridge over the river.
"Construyendo" serves as a gerund in this context, modifying the main clause by expressing an action concurrent with the main verb.