Hi please help.

used to say that one believes that something is true, that a particular situation exists, that something will happen, etc.
"Has she accepted the job?" "I think so."

2
—used to express a positive opinion about a question one has just asked
Is this a good use of our tax dollars? I think so.

What's " I think so" in these two sentence?

Is it equivalent of" yes"?

Question

Hi please help.

used to say that one believes that something is true, that a particular situation exists, that something will happen, etc.
"Has she accepted the job?" "I think so."

2
—used to express a positive opinion about a question one has just asked
Is this a good use of our tax dollars? I think so.

What's " I think so" in these  two sentence?

Is it equivalent of" yes"?

Answer

I think so is less certain than yes. It shows that you think what you say is the truth, but you're short of complete certainty.

You can use I believe so, for example, as an alternative to I think so.

Yes is a positive response that confirms or agrees to something. It is definite.

لا تفوّت فرصة تعلّم لغة جديدة وأنت مرتاح في منزلك. تصفّح مجموعتنا المختارة من مدرّسي اللغات ذوي الخبرة وسجّل في درسك الأول الآن!