The translation above is what the dictionary says, but a "praatjesmaker" is not necessarily somebody who boasts, but more like somebody who is all talk and no action, doesn't live up to what he/she claims, talks nonsense, claims to know what he/she is talking about but not really, a smart talker etc.
The noun is derived from "praatje" and "maken". The verb is "praten": to talk. A "praatje maken" in general is "to have a brief informal conversation with somebody". See the expressions below for more.
– "Hoe was de lezing van Frank?" – "Het sloeg helemaal nergens op; weet je, het is gewoon een praatjesmaker."
("How was Frank's lecture?" – "It did not make any sense at all; you know, he is just all talk and no action.")
– "Let wel, op praatjesmakers zitten we hier niet te wachten; wij verwachten inzet en kunde!"
("Be aware, we have no need for boasters; we expect dedication and skills!" Lit. "we are not waiting on boasters here".)
– "Zeg praatjesmaker, nu is het genoeg geweest; het is tijd om naar bed te gaan!"
("Hey mister know-it-all, that's enough now; it's time for bed!")
– "Een praatje maken met iemand": to briefly and informally chat with somebody.
– "Praatjes hebben": to talk big, to be a 'know-it-all'.
– "Let maar niet op hem; hij heeft praatjes."
("Don't mind him, he is just talking big.")
– "Mooie praatjes": sweet talk.
– "Een praatje houden": informal way of saying "to give a lecture". Note the use of "houden": to hold; this is the reason Dutch people often say they have to "hold a speech".
– Praten: to talk [verb] [praatte, gepraat].
– Praatje: quick conversation, lecture [noun] [het praatje, de praatjes].
– Onzin: nonsense [noun] [de onzin, <no plural>].
– Liegen: to lie [verb] [loog, gelogen].
– Opscheppen: to brag/boast [verb] [schepte op, opgeschept]. Note this verb also means to serve/spoon/ladle out (as in putting food on your plate).