‘Indicative’ indicates a state of factuality or states something that is happening in reality. Most sentences in English are written in the indicative mood. For example, the sentence –
The dog jumps into the car
– simply states what is really happening in the present moment.
The indicative mood can also be used in sentences that include words like ‘might’ or ‘may’ because it indicates something that is a real possibility:
That house might collapse if they don’t make the necessary repairs.
The fact that the house could actually fall down if it isn’t fixed is indicative of reality, so we would say this sentence is written in the indicative mood.