Can someone explain me this diagram from an article? How should I understand this 59 degree mentioned below, what does it mean? I could not get it. The photo is a diagram from an article dedicated to the invention of the ecliptic. The photo is from my tablet (the title could be seen)
The Earth's equator is at an approximate 23.4 degree angle to the plain of its orbit around the Sun. That means that to an Earth-bound observer the Sun appears to move north and south of the celestial equator (which is merely the projection of the Earth's equator on to the sky) during the course of the year.

In fact this is what gives us the seasons - so in the the Sun is at maximum northern declination (the equivalent of latitude when projected on to the sky) at the time of the Summer Solstice (around 21 June - hence summer in the northern hemisphere) and at maximum southern declination at the time of the winter solstice (around 21 December - hence northern winter). 

But this movement also means different rising and setting points - in the Northern hemisphere the Sun's rise is between north and ast in the summer and between south and east in the winter (unless, that is, you are within the Artic circle in which case it will not set/rise at all for at least some period in the summer and winter).

There are a variety of online tools that show you this effect - this one: https://www.timeanddate.com/sun/iraq/baghdad?month=12&amp;year=2017 - shows that in Baghdad the sun rises - in 2017 - at 61 degrees East on 21 June and at 118 degrees East on 21 December - a difference of 58 degrees.