Meaning sentence:

Question

In this example: Esther ha podido reservar una mesa esta mañana.Why the speaker can see him/herself in this time frame? It's obvious that the speaker is talking about someone else.Thank u so much

Answer

Hola EmmaThe use of "esta mañana" triggers the use of the perfect (in Peninsular Spanish). The speaker, even though they are not the subject of the sentence, is in the same time frame as we are talking about the same morning. The speaker is inside that same morning: this morning.I hope it clarified it.Saludos

Answer

I have the same question, what does it mean for a speaker to see itself in the statement? The previous answe doesn't make it clear to me.

What are statements with time frames in which a speaker doesn't see itself? For example, what verb tense would be used without esta mañana. What are other examples?

Answer

Hola Cassandra
Here's a lesson that goes into more detail on this and it contrasts the perfect tense with the preterite. The concept of "being/feeling in the same timeframe" is a bit difficult to see, but what it means is that the speaker sees himself/herself still being inside that period of time, so it's not completed, it's still ongoing and is part of the present time. Phrases like esta mañana, esta tarde, hoy... are typically used with the perfect because the day we are referring to has not passed yet. However if we talk about things that happened "yesterday" (ayer) we use the preterite instead, because that day is over, we are now in a new day, so those actions are seen as finished and completed. 
Saludos