This is essentially an Assessment Centre, Deza.
If you type the word into Google you may find some helpful ideas from some of the better recruitment organisations that explains the principles.
The verbal and numeric tests will almost certainly be a test of your reasoning ability. You can't really practice for these - they are a powerful indicator of innate intelligence - though not foolproof because some people just can't do tests.
The Group Exercise will involve you and other recruits given some sort of task to deliver against time pressure. You will be watched around the outside by observers and possibly the group will be asked questions about how they felt it went afterwards. These type of exercise is designed to help the recruiter determine your likely behaviour in when working in teams. Try and avoid either overdominating the exercise, or contributing little. If you have ever seen The Apprentice programme, think carefully about how those poor chaps get thrown together in the early programmes when they don't know one another. Success in completing the TASK is not relevant - never forget that - what the observers are looking for is the PROCESS by which the team works. While you are engaging yourself - try and think about what is going on in the background - who is leading, who is dominating, who is doing nothing to contribute and try and get your points (words) and actions across in a persuasive way. It is probably best to try and avoid being the task leader - too risky - as you will have seen on The Apprentice.
If you know something about Belbin Team Roles, look at it again this weekend. Or search on it. Also try searching on 'group dynamics'.