I've looked up a ticket for a connection from Brussels to Den Haag, with a five minute connection in Breda. This connection is suggested by the railway company, is that some kind of commitment that this connection is reachable?
When you have a train ticket this is a commitment by the railways to get you to your destination. In your case your ticket is for Brussels to Den Haag so to Den haag the railways must get you.
But it doesn’t have to be with the trains you originally intended to use. The fact that you change in Breda tells me you have a ticket for the IC train. That ticket is valid for a whole day on all trains on the Brussel - Breda - Den Haag route. That means you can also take one of the direct trains. Or you can choose to transfer in Rotterdam in stead. Staying on the train till Rotterdam and changing there has some advantages. There are like 8 trains per hour from Rotterdam to Den Haag, so if you miss one you do not have to wait long for the next one...
Breda is already in the Netherlands and the most common method for this kind of tight connections is that one train comes in, stops on one side of a platform, then the other train comes in on the other side of the same platform, stays for a few minutes, so every body gets out and in, last in train leaves first, first train in leaves last.
So while the connection is about 5 minutes, it is not rushed, as you only have to cross the platform. If you give more details I can look up the details. (Or you can look them up yourself. On the Dutch railways planner, here in English.)
In the Netherlands, platforms are given for each train, as part of the normal train table information. Rarely the station has to announce changes but as a rule the trains leave from the platforms as announced.
Even when you have to change to one of the other platforms, 5 minutes is the norm rather than short. There are stairs on both ends of the platforms and only 3 (double sided, so 6 numbers) of them.
And as a rule these trains run every 30 minutes, often with an alternate connection in between for busy routes, you will not run much risk unless you have an ongoing connection to a different kind of transport that is running less often.
It is doable, but quite tight, especially if you have a lot of luggage.
The train from Brussels will usually arrive in Breda on track 5 and the train to Den Haag will depart from track 7, which is a different platform. You will either have to take the stairs or the elevator down to a connecting corridor and then up again to reach the correct platform. Especially if you prefer to use the elevator, it is not unlikely that you will queue up with other passengers and not have time to catch the next train.
I lost a train in Utrecht because of that tight time schedule of five minutes. That time my platform for the next train changed. Since I went to the platform printed in my ticket I arrived to the wrong platform, without enough time to realize that my platform was modified.
Hence, you can do it in five minutes, but do not forget to listen the audio messages, you might lose important information about last minute changes.
That time they gave me a new ticket without additional cost.