Whenever you want to report to a friend of yours what someone else has said to you before or even if you simply repeat what you have just said a few minutes ago, you use the indirect speech. The reported information is introduced with ‘dass’, a side-clause-conjunction. Let me clarify with the help of a few examples:
"Ich komme fünf Minuten später." I will be five minutes late.
Ich habe gesagt, dass ich fünf Minuten später komme. I have said that I will be five minutes late.
Vater: “Ich bin um fünf zuhause.” I will be home at five.
Sohn: Mein Vater hat gesagt, dass er um fünf zuhause ist.
Don’t bother with the change to Konjunktiv I or II that you might find in some German textbooks at this level. That will be covered in B2 or higher. For now go with the Präsens tense.
Not much more to say here. Remember that side-clauses need their verbs (the ones with the personal ending) at the very end. And also note the change in the second example from ich to er. This change should become obvious to you as soon as you read the translations. The following phrases can be considered introductions of a report of what you think, believe or see etc.:
Ich denke, dass... I think that...
Ich glaube, dass... I believe that...
Ich sehe, dass... I see that...
dass-sentences are so called content-sentences. That means that the dass-sentence contains the content of the word that precedes it. In „ Ich denke, dass...“ the dass-sentence contains the content of the „denke“, meaning the actual thoughts.
This topic is covered in: A2-L25