Man: What do you do when you do the accounts?
Woman: I make out checks. So much to do and so little time to do it in.
Man: Do you think you’ll make it?
Woman: Sure. I’ll make it.
Man: But do you make enough money for everything you do?
Woman: Just enough. I make do.
Man: So do I. I make do as well. I get by. I get up in the morning. I get dressed. I get on the bus. I get off the bus. I get to work.
What does “I make do” mean?
Thank you
It means to get by, to manage.
Thank you so much, Torsten 
This means that I do (follow) it too. (I make do it too)
Thank you so much, Anglophile
The key words are in bold. When someone says they make do, it means they just barely have enough money. It means if they are thrifty they have enough money for the most important things, but not enough for more than the basics.
Thank you so much, NearlyNapping
Very nice.
I have one more question:
.
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Man: Do you think you’ll make it?
Woman: Sure. I’ll make it.
.
.
What does “I’ll make it” mean here?
Thanks
Since she has very little time, I would say that the woman thinks that the man wants to know if she has enough time to do it, but what he actually wants to know is if she has enough money. Why else would he ask: But do you make enough money for everything you do?
…make it
This is used in many contexts. Since this follows the woman saying she has so little time, it means she will complete the task on time.
I’ll make it [ on time ].
Other contexts
A: Can you jump across the creek?
B: I think I can make it [ across ].
A: You look very tired. Do you think you can complete the race?
B: I think I’ll make it.
It can be sarcastic.
A: That is a serious wound. Do you think you’ll make it?
( the wound is obvious not serious )
B: I think I’ll survive.
Thank you so much, Masme
Thank you so much, NearlyNapping.
Very nice.
You’re welcome.