Final answer:
The letter 'H' in the name of a Direct TV IRD signifies that the device is high-definition capable, enabling reception and processing of HD content.
Step-by-step explanation:
When you see the letter H in the name of a Direct TV IRD (Integrated Receiver/Decoder), it indicates that the device is high-definition (HD) capable. This means the receiver can receive and process HD signals, allowing you to watch content in high-definition on your television. Direct TV provides a variety of receivers and the 'H' models are designed to deliver improved image quality compared to standard definition models.