Any existing belongings to take from previous home to your home for familiarity will help eg blankets, bowls or toys, leads, harness.
It takes 3 months+ for them to settle into their new home, learn new boundaries, recognise new sounds and smells.
It’s like us upping sticks and learning a new language in a different country. Try & find out which words the dog is already used to rather than introduce new ones for already learned techniques eg ‘heel‘ if s/he knows that instead of ‘here’ if they don’t know that.
The new addition may make new sounds so you’ll need to try and learn the body language as to whether they’re comfortable or asking you to back off.
H/she may be lonely, want company all the time or need time out. You need to go with what you feel they’re asking for and provide it if this is going to work.
Boundaries will need to be set and trust has to be earned from all parties. It can be hard work but it’ll be worth it.
Dogs do talk...but only to those that listen.
Very well done for taking this dog on, you’re a star x