For absolute clarity, adjectives are a category of words commonly referred to as 'describing words' (e.g., beautiful, large). They give attributes to a noun, or 'naming word' (e.g., cat, city), thereby describing its qualities.

In your efforts to describe things in your writing, you might find yourself doing lots of this:

The stunning, ornate entryway was a spectacular example of Victorian Gothic architecture, its large, imposing stone columns giving off a foreboding, awe-inspiring aura.

While the above example does provide a clear image of the thing it's describing, it is heavily reliant on the use of adjectives, several of which are similar in meaning. Further, there are three instances where more than one adjective is used to modify a single noun. This is called an adjective phrase, and using too many of them can quickly overwhelm your writing.

Adjectives are not inherently bad. In fact, they're necessary to make meaning. If we were to remove all adjectives and adjective phrases from the above example, we'd be left with this:

The entryway was an example of architecture, its stone columns giving off an aura.

Amusing, but not very informative!

The first half of the sentence now only states the obvious, giving no details about the entryway or the narrator's perception of it. And without an adjective to describe the aura in the second half, there's no longer any sense of the impression the entryway gives, rendering having mentioned it at all almost pointless.

Let's look at the example again with only the bare essentials:

The entryway was a spectacular example of Victorian Gothic architecture, its stone columns giving off a foreboding aura.

Now that we've done away with the fluff, things are looking much tidier ... but we may have gone a step too far. Though the meaning has indeed been restored, something about the feeling has been lost.

The absence of 'stunning', 'ornate', and 'awe-inspiring' has little to no impact on the visual, which is a good indication that they're unnecessary. But without 'large' and/or 'imposing', there's no sense of the columns' scale, which is a big part of what gives them their imposing aura.

Let's try one more time:

The entryway was a spectacular example of Victorian Gothic architecture, its monolithic stone columns giving off a foreboding aura.

On its own, 'imposing' might imply that the columns are large, but it doesn't expressly communicate it, and could be construed as doubling up on 'foreboding'. As for 'large' ... well, it's just a bit boring by itself, and doesn't work hard enough to convey the image.

With 'monolithic', we've pared the use of non-essential adjectives right back from four to one, preserving the imagery and leaving the sentence far less bloated. Some purists argue that even one unnecessary adjective is too many but personally, if it adds flavour, then I'm all for it.

The goal is not to eliminate the use of adjectives, but to use them sparingly, and to break the habit of throwing in as many as possible. If they're not helping you get your message across, you don't need 'em.