Everything you need to know about the brown dwarf that is the primary of this system is here:

https://en.wikipedia.org/wiki/TRAPPIST-1

But there is one phenomenal, but completely unexpected coincidence. Like the fact the apparent sizes of the lunar and solar discs are essentially identical (making spectacular solar eclipses possible), this brown dwarf is only 40' of arc away from our ecliptic. That's just a little more than one full moon diameter.

We can use the transit technique to detect these planets, which means Sol, as seen from Trappist-1, is on ITS ecliptic plane. An observer on one of these planets would be able to use the transit technique to detect the planets in our solar system, watching them cross in front of the Solar disc.

It has been remarked that stars near our ecliptic plane would be able to use the transit technique to determine our solar system had planets. Assuming the transit technique is favored by alien astronomers to search for planets, it is highly likely if ETI ever calls here, he will probably be from a world near our ecliptic. However, since ecliptic planes are randomly distributed in space, it is highly unlikely we would be able to do the same for any of these worlds. But in this case, by an incredible coincidence, observers in each system would be able to detect planets in the other.

So what physical significance does this have? What does it all mean? Absolutely nothing. Its just a coincidence. But don't tell Johannes. 8)