nod your head & smile
You are who you are. Do the best you can and don't pretend you understand what's being said if you really don't understand. You won't look stupid for asking to have things repeated.
If the consultant is in your country, shouldn´t he/she speak to you in your own language ?
That being said, if this a very important issue my advice for you is to hire an Interpreter.
Be yourself, do the best you can, and try not to be nervous.
If you have a good friend who speaks English and you don’t mind them coming / they are available then take them with you….
Otherwise I would write down the key words - then at least is you have a problem with pronunciation you can show them...
prepare whatever is important to say by writing it down as important points in proper language and rehearse it few times