I am on vacation
Use when you are specifically traveling away from home.
Literally "I took some free days." Use this for a short break from work, not necessarily a big trip.
Means "I am resting." A good option for a 'staycation' or a quiet vacation at home.
I can't answer my cell phone, I'm on vacation with my family.
—Why aren't you at the office? —I took a few days off.
This month I'm traveling through Colombia.
Don't worry about work. You're on vacation!
The phrase 'Estoy de vacaciones' is the universal standard and understood everywhere in the Spanish-speaking world.
Usage is identical to Latin America. 'Estoy de vacaciones' is the most common phrase.
In casual conversation, you might hear 'Ando de vacaciones', which has a similar meaning to 'I'm out on vacation'.
While 'Estoy de vacaciones' is common, it's also very frequent to hear 'Me tomé vacaciones' or 'Me tomé unos días'.
Using 'soy' instead of 'estar' (e.g., 'Soy de vacaciones'). — Vacation is a temporary state, not a permanent characteristic. Always use 'estar': 'Estoy de vacaciones'.
Using the wrong preposition (e.g., 'Estoy en vacaciones'). — The correct and fixed expression is 'de vacaciones'. Think of it as being 'of vacation' rather than 'in vacation'.
Using the singular form (e.g., 'Estoy de vacación'). — In Spanish, 'vacaciones' is almost always used in its plural form, much like 'pants' or 'scissors' in English, even when referring to one vacation period.