My Senior told to me that, using disavow link tools, we can remove the low-quality links, and it will help us to rank in SERP. but no idea that if we remove back link how could we get Better SERP
Well, your senior is correct on this one that using Disavow tool can help you in getting rid of the bad backlinks, so the idea here is suppose you have seen a link which is really low quality and you dubt that it will in future takes you toawrds the path of penalty then you can use your disavow tool over it put the link over to the disavow tool and now when serps rank you over the search engine they will not consider that link to rank you over the SERPS, it like in a school teacher give you the freedom to came to class at anytime, he's not going to marke your attendance based on the time you have reached the class. One more thing use this tool wisely because it's a powerful tool and I am sure you must be pretty much aware that power comes at a cost. Better option would be first try talking those low quality links down by contacting the owner of that site at personal level and if you can't reach then or he ask for money to remove the links then you should move ahead and use disavow tool.
Well, @harrykingsville I haven't talked about blog commenting or linking over here or nor do the @OP of this question wants to know about, he want's to know about the disavow tool available over the Google Webmaster page.
@Reuben1 Yes you are correct, this tool isn't something like clearing up the links and now you will start ranking on top of everything rather than its like an way to help you in getting out of the trouble and using it if you get out of the trouble further your work is going to put you on top of the list !
low quality links, paid links and spammy links is also known as disovow links. Disovow links can be remove with the help of disovow tool in webmaster. if you remove these links then you will get postive results. Google do not like these links. if all the links of your site is good then it must be very helpful to get better search rezults.
Well, @davijhon it do seems that you have written the answer pretty much well and I seem to agree with you on this one over here, but I would say the last link "all the links of your site is good then it must be very helpful to get better search results" I guess what you are trying to say over here is, if all the links to your site is good then it's very helpful in getting yourself ranked much better over the search results.