B-Line Eaton series imperial cable tray and ladder, 4" Height, 30" Length, 6" Width, Series 2-5 horizontal tee, Aluminum, 24" Radius

It means the tee turns with a 24 inch inside bend radius, which is the figure your cable manufacturer's minimum bending radius gets checked against. Large power conductors and fiber often call for a wide radius, and 24 inches is the widest of the common tray fitting radii. If your cable allows a tighter bend, a 12 inch or 36 inch radius version of the same tee is the alternative to look at.

Aluminum. That matters on two counts: it keeps the fitting light for overhead work at about 19.127 lb, and it holds up better than plain steel in damp or corrosive areas. Aluminum tray also has to be bonded per NEC requirements for the system to be used as an equipment grounding path, so plan your bonding jumpers across the splice plates.

Allow for the 30 inch overall length of the fitting plus clearance on the branch leg. With a 24 inch radius and 6 inch tray width, a wide sweep tee eats real estate, so check your ceiling or rack space before committing to it instead of a tighter radius fitting.

Yes, plan on them. The 4A-06-HT24 is the tee body only; each of its three ends joins to straight tray with splice plates and hardware ordered for the matching Series 2-5 imperial profile. Count three connections per tee when you build the bill of material, and add support hangers where the fitting lands, since a tee is a load point in the run.