لا يوجد تخييم ولا جولة إرشادية اليوم.

لا يوجد is a very common MSA way to say there is not / there are not.

• لا negates the verb
• يوجد means exists / is found

So the structure is literally something like Camping and a guided tour do not exist today, but in natural English it becomes There is no camping and no guided tour today or There is no camping or guided tour today.

No. That is an important distinction.

In لا رجلَ في البيت, لا is the special grammar pattern often called لا النافية للجنس, where لا directly governs the noun.

In لا يوجد تخييم..., لا is simply negating the verb يوجد. So the sentence is a normal verbal sentence, not the special لا رجلَ type.

That is why the nouns here are not in the لا رجلَ pattern. If you fully vocalized them, you would have تخييمٌ and جولةٌ, not forms like تخييمَ and جولةَ caused by that other kind of لا.

Because Arabic often keeps the verb singular when the verb comes before its subject, especially in existential-style sentences like this.

Here, يوجد is the normal singular form used in there is/there are expressions. English changes between there is and there are, but Arabic does not always mirror that the same way.

Also, the first item mentioned after the verb, تخييم, is singular in form, so يوجد sounds completely natural here.

تخييم is a verbal noun (called a maṣdar in Arabic grammar). It means camping as an activity.

So:

• تخييم = camping
• not a finite verb like to camp
• not the place itself

If you wanted to talk about a camp as a place, Arabic would usually use a different word, such as مخيّم in many contexts.

Because ولا is very common in Arabic after a negative statement to mean and no, nor, or what English often expresses with or.

So:

• لا يوجد تخييم ولا جولة إرشادية
• literally: There is no camping and no guided tour
• natural English: There is no camping or guided tour

Arabic often prefers ولا in this kind of negative list, where English commonly uses or.

Because the adjective must agree with the noun.

جولة is:

• feminine
• singular
• indefinite

So the adjective إرشادية must also be:

• feminine
• singular
• indefinite

That is why you get:

• جولة إرشادية = a guided tour

If the noun were masculine, the adjective would be masculine too. If the noun were definite, the adjective would also become definite.

Because the phrase is indefinite.

• جولة إرشادية = a guided tour
• الجولة الإرشادية = the guided tour

In Arabic, adjectives match nouns not only in gender and number, but also in definiteness. So if the noun has ال, the adjective normally has ال too.

Because اليوم can function directly as an adverb of time, meaning today.

Arabic often uses time words this way without a preposition:

• اليوم = today
• غدًا = tomorrow
• أمس = yesterday

So اليوم here simply tells you when the lack of camping and guided tours applies.

One fully vocalized version is:

لا يُوجَدُ تَخْييمٌ ولا جَوْلَةٌ إِرْشادِيَّةٌ اليَوْمَ

A few useful points:

• يُوجَدُ = the verb
• تخييمٌ = nominative
• جولةٌ إرشاديةٌ = also nominative
• اليومَ = accusative as an adverbial expression of time

In normal modern writing, these short vowels and case endings are usually omitted, so you normally see:

لا يوجد تخييم ولا جولة إرشادية اليوم.

Yes. That is also correct and common.

Both of these are standard ways to express there is/there are not in MSA:

• لا يوجد تخييم ولا جولة إرشادية اليوم
• ليس هناك تخييم ولا جولة إرشادية اليوم

The version with لا يوجد is very common in formal written Arabic and public notices. The version with ليس هناك is also natural and clear.