“¿Esto es un baño?” Would be “Is this a bathroom?” If you were pointing at the door I think any spanish speaker would understand. Though I would use “¿Aque es el baño?” Which would be closer to “Is this the bathroom?”

If you weren’t pointing at a door and want to ask where the bathroom is it’d be “¿Dónde está el baño?” Translation: “Where is the bathroom?”. Other options are

• “¿Me enseñas dónde está el bano?” = Can you show me where the bathroom is?

• “¿Puedo usar tu baño?”= Can I use your bathroom?

• "¿Tienen un baño que puedo usar?= Do you have a bathroom I could use? Or just “¿Tienen un baño?”= Do you have a bathroom.

“Lo siento no habló español” is “I’m sorry I don’t speak Spanish.” Alternatives:

• “Lo siento no habló hablo mucho español.” = I’m sorry I dont speak much spanish.
• “Lo siento no sé mucho español.” = I’m sorry I don’t know a lot of spanish.
• “Lo siento nomas sé poquito español.” = I’m sorry I only know a little spanish.
• “Lo siento nomas puedo hablar poquito español.” = I’m sorry I can only speak a little spanish.

Either sentence could be started with a form of “disculpa”. But honestly my thumbs are getting tired of typing so I’m just going to leave it there.