Why there is no 5g band on iphone 13 pro

On the side? You mean antenna band. Were you expecting one?

Model A2638*

• 5G NR (Bands n1, n2, n3, n5, n7, n8, n12, n20, n25, n28, n30, n38, n40, n41, n48, n66, n77, n78, n79)
• FDD-LTE (Bands 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 30, 32, 66)
• TD-LTE (Bands 34, 38, 39, 40, 41, 42, 46, 48)
• UMTS/HSPA+/DC-HSDPA (850, 900, 1700/2100, 1900, 2100 MHz)
• GSM/EDGE (850, 900, 1800, 1900 MHz)

Model A2643*

• 5G NR (Bands n1, n2, n3, n5, n7, n8, n12, n20, n25, n28, n30, n38, n40, n41, n48, n66, n77, n78, n79)
• FDD-LTE (Bands 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 30, 32, 66)
• TD-LTE (Bands 34, 38, 39, 40, 41, 42, 46, 48)
• UMTS/HSPA+/DC-HSDPA (850, 900, 1700/2100, 1900, 2100 MHz)
• GSM/EDGE (850, 900, 1800, 1900 MHz)

All models

• 5G (sub‑6 GHz)5
• Gigabit LTE with 4x4 MIMO and LAA5

iPhone 13 supports 5G networks. Different carriers call it different things ... LTE is a common choice for carriers to name it.