Final answer:
To describe an action currently in progress, the Spanish verb 'estar' should be used. 'Ser' is for permanent states or characteristics. Choosing the correct verb is essential as the meaning of a sentence can significantly change.
Step-by-step explanation:
To describe what is going on right now, or an action that is currently happening, you would use the verb 'estar' in Spanish. For example, if you want to say 'I am eating', you would say 'Estoy comiendo.' The verb 'estar' is used for actions that are taking place at the moment of speaking, and it indicates a temporary state or condition.
The verb 'ser', on the other hand, is used to describe more permanent states, characteristics, or to tell the time, date, or place of an event. For instance, to say 'I am a teacher', you would say 'Soy profesor,' because being a teacher is considered a permanent part of someone's identity.
It's important to choose the correct verb between 'ser' and 'estar' because they can change the meaning of a sentence substantially. This is one of the fundamental aspects of Spanish grammar that distinguishes it from English, where the verb 'to be' does not change based on permanent or temporary states.