Learn Spanish (Latin America): ¿Estará sosteniendo un globo ficticio?

In Spanish, the future tense is frequently used to express a guess, wonder, or probability about the present. By using the future progressive (estará + the gerund sosteniendo), the speaker is wondering about an action happening at this exact moment: "I wonder if he is holding..." or "Could he be holding...?"

Could I just use teniendo instead of sosteniendo to say "holding"?

While tener generally means "to have," sostener specifically means "to hold" in the sense of physically supporting or gripping something in your hands. Since the sentence is about physically holding a balloon, sosteniendo is the most accurate and natural choice here.

If I translated this literally as "Will he be holding a fictional balloon?", would that be wrong?

It wouldn't be grammatically wrong, but it changes the meaning. In English, "Will he be holding..." usually asks about a literal future event. Since the Spanish sentence is using the future tense to guess about the present, translating it with "Could he be..." or "I wonder if he is..." captures the speaker's true intent much better.

Does globo always mean "balloon"?