If you're talking about a location:
* Je suis à... (formal) - This is the most common and literal translation.
* J'y suis. (informal) - This is used when the location has already been mentioned.
Example:
* "I am at the library." -> "Je suis à la bibliothèque."
* "I am at the party." -> "J'y suis." (after someone asks if you're at the party)
If you're talking about a state or activity:
* Je suis en train de... - This means "I am in the process of..."
* Je suis à... - This can also be used to describe a state, but it's not as common as the previous phrase.
Example:
* "I am at work." -> "Je suis au travail."
* "I am at dinner." -> "Je suis en train de dîner."
Other possibilities:
* Je suis dans... - This means "I am in..." and can be used for location or a general state.
Example:
* "I am at a difficult time." -> "Je suis dans une période difficile."
The best translation will depend on the specific context.