Meaning and local context
In Liverpool, “sound” means Good, trustworthy, agreeable, or okay. Used for people, plans, and reassurance.
Example in context
A local example is “She is sound, you can trust her.” In plain English, that means “She is trustworthy and friendly.”
She is sound, you can trust her.
She is trustworthy and friendly.
How to interpret it
The surrounding sentence is important when interpreting “sound”. Use the regional sense above when the situation matches the example instead of relying on the word or phrase in isolation.
Tone and caution
Tone determines whether it means sincere approval or simple acceptance. Because this is informal regional language, tone and situation should guide whether you use “sound” yourself or simply recognise it when someone else uses it.