The MGNTB2504 is a 4-pole Isobar B terminal block rated for 250 A at 415 V AC — a high-current distribution point for panel builders who need a single through-feed extension rather than a multi-way distribution block. The cable stiffness spec (Flexible 95 mm² / Solid 120 mm²) tells you the maximum conductor cross-section the clamp accepts; the 15 N.m tightening torque is what you set the driver to for solid conductors at the upper end of that range.
What the 250 A rating means for fit
That is the figure to match against your load: if your circuit draws 250 A or less at 415 V, this block is electrically sized for it. The 4-pole configuration (4P) means it handles all three phases plus neutral in one assembly, which saves rail space compared to ganging four single-pole blocks.