Final answer:
The subject of this question is English, and the sentence 'I'm suspending you indefinitely' is an example of declarative speech.
Step-by-step explanation:
The subject of this question is English. The phrase 'I'm suspending you indefinitely' is a statement made by someone in a position of authority, indicating their intention to impose a suspension on someone with no specified end date. In English, this sentence is an example of declarative speech, where the speaker makes a straightforward statement or assertion.