what gives bread its tast is it salt or what sometimes bread taste very bland
Read up on slow fermentation and overnight fridge retardation. Basically the slower/longer your bread rises, the tastier it will be.
There are many many threads on TFL regarding this.
I agree with dwcoleman, but salt is a flavor enhancer. Without it the bread will have less flavor.
sometimes bread tastes very bland
There's nothing intrinsic about bread that requires it to taste bland ...it does happen a lot though. Making bread not taste bland is a big part of what TFL is all about. Lots of different factors contribute (you probably won't find a one-size-fits-all answer). Some methods are honest, others are "cheating" (for example "just add more sugar").
As a very rough rule of thumb, all the things that allow commercial operations to produce bread easier/faster/cheaper also mean less taste. You could think of it sort of like a teeter-totter with "business" on one side and "taste" on the other side, or you could think of it as sort of analogous to storebought vs. homegrown tomatoes, or... You can get some very tasty breads indeed from specialty bakeries, but you'll pay lots more than supermarket prices for them.
Salt and sugar compliment each other. The craft of the baker is to use their skill to blend the two together.
I'll add that lack of salt may cause lack of flavor two ways. One is that without salt, bread, like many things, lacks savor simply on account of salt's flavor enhancing role. Another is that lack of salt can fail to retard yeast activity enough, so that yeast grows quickly and doesn't leave time for flavor to form. A useful exercise for newer bakers is to taste at every stage. For instance, a bread that begins with a starter and has multiple rises. Taste the newly made starter. Nothing but the bland flour taste. Uninteresting and unappealing. 18 hours later, the starter has acquired considerable flavor. After the dough has been through multiple rises, the flavor is more pronounced and, I think, smoother and more interesting. Salt allows that process to work over a longer time to create more flavor. Straight artisan breads with only the four basic components are flavorful directly in relation to how long they work.