Turbo bracing is support for your turbo/manifold or down-pipe to prevent parts cracking, bracing also helps prevent bolts nuts & studs loosening from excess weight. A well designed brace also helps take the weight off the inlet and outlet vband clamps on turbine housings that are used to tighten the vband flanges in place.
Turbo support is a big part of the reliability of any turbo setup, the combination of immense heat and vibrations from high revving engines is enough to test even the toughest components.
The main thing to consider when designing bracing is "thermal expansion", whenever things get hot they expand and this needs to be thought about before bracing your turbo setup. Making everything to solid can sometimes cause more harm than good.
A prime example...... welding solid braces from your exhaust manifold flange to your turbo flange. If the brace is short or to thick it can't flex and there is no allowance for anything to move when it heats up, so generally the brace will always crack over time - the longer the distance the more the rods or brace can flex.
A rose joint type brace like in the photo are a excellent way to gain a lot of movement from a brace, they still take the weight while still pivoting easily when the manifold moves from thermal expansion.