Die Suppe ist leicht salzig.

Because Suppe is a feminine noun in German. Its dictionary form is die Suppe.

German nouns have grammatical gender:

• der = masculine
• die = feminine
• das = neuter

So in the nominative singular, die Suppe is the correct form.

It is in the nominative case because it is the subject of the sentence.

In Die Suppe ist leicht salzig, the soup is the thing being described, so it is the subject:

• Die Suppe = subject
• ist = verb
• leicht salzig = description

Because German main clauses normally follow the verb-second rule.

In a basic statement, the conjugated verb usually comes second:

• Die Suppe = first element
• ist = second element
• leicht salzig = the rest

This is very normal German word order for a simple statement.

Because sein (to be) is used to describe a state or quality.

Here, ist links the subject to an adjective:

• Die Suppe ist salzig.
• Das Wetter ist gut.
• Der Kaffee ist heiß.

This works like English is in sentences such as The soup is salty.

Because salzig is being used as a predicate adjective, not directly before a noun.

In German:

• before a noun: the adjective usually takes an ending
  
  • die salzige Suppe
• after sein / werden / bleiben: the adjective does not take an ending
  
  • Die Suppe ist salzig.

So salzig stays in its basic form here.

Here, leicht means slightly, a little, or mildly, not light in the physical sense.

So leicht salzig means something like:

• slightly salty
• a bit salty
• mildly salty

In this sentence, leicht functions like an adverb modifying salzig.

Because here leicht is functioning as an adverb, not as an adjective directly modifying a noun.

Compare:

• eine leichte Suppe = a light soup
  Here leichte describes Suppe, so it gets an ending.
• Die Suppe ist leicht salzig = The soup is slightly salty
  Here leicht modifies salzig, so it does not get an ending.

Yes. That would simply mean The soup is salty.

Adding leicht softens the statement:

• Die Suppe ist salzig. = clearly salty
• Die Suppe ist leicht salzig. = somewhat / slightly salty

So leicht makes the description more precise.

Yes, absolutely.

There is a small difference in focus:

• Die Suppe ist leicht salzig. = describes the soup’s quality
• Die Suppe schmeckt leicht salzig. = describes how the soup tastes

Both are natural, but schmeckt is especially common when talking about flavor.

In German, all nouns are capitalized. That is why Suppe starts with a capital letter.

Adjectives and adverbs are normally not capitalized unless they begin the sentence or are used as nouns.

So:

• die Suppe → noun, capitalized
• salzig → adjective, not capitalized
• leicht → adverb here, not capitalized

In standard German, salzig is usually pronounced approximately as ZAHL-tsikh.

A rough breakdown:

• sal- sounds like zahl
• -zig often sounds like tsikh in careful standard pronunciation

The final -ig in standard German is often pronounced like -ich in many words:

• salzig → /ˈzaltsɪç/

But pronunciation can vary by region.

Yes. salzig comes from Salz, which means salt.

So:

• das Salz = the salt
• salzig = salty

This is similar to English:

• salt
• salty

Normally, no, not in standard German.

In a regular sentence, a singular countable noun like Suppe usually needs an article or another determiner:

• Die Suppe ist leicht salzig.
• Diese Suppe ist leicht salzig.
• Meine Suppe ist leicht salzig.

Without die, it sounds incomplete in standard usage.

It would be:

Die Suppen sind leicht salzig.

Changes:

• Suppe → Suppen (plural)
• ist → sind (plural verb)

So the structure stays the same, but the noun and verb agree in number.