Bij de volgende kruising moet je eerst links kijken, ook als het fietspad vrij lijkt.

Because Dutch is a verb-second (V2) language in main clauses.

In this sentence, Bij de volgende kruising comes first. Once that first position is taken, the finite verb has to come next:

• Bij de volgende kruising moet je ...

So the subject je moves after the verb.

Compare:

• Je moet eerst links kijken.
• Bij de volgende kruising moet je eerst links kijken.

Both are correct; the difference is just what comes first in the sentence.

Here bij means something like at, when you get to, or on reaching the next intersection/crossing.

It does not necessarily mean physically next to in a literal sense. In traffic instructions, bij is very common for the point where something happens:

• Bij het stoplicht moet je wachten.
  = At the traffic light, you have to wait.

So Bij de volgende kruising means at the next intersection or when you reach the next intersection.

Because kruising is a de-word in Dutch:

• de kruising = the intersection

Since it is a de-word, you say:

• de volgende kruising

Also, the adjective volgende gets -e before the noun in this kind of phrase. So:

• de volgende kruising
• het volgende fietspad would be different only because fietspad is a het-word

Because the sentence uses the modal verb moeten (must / have to).

With a modal verb in Dutch:

• the finite modal verb comes earlier in the clause
• the main verb stays in the infinitive and usually goes to the end

So:

• moet je ... kijken

Compare:

• Je kijkt links. = You look left.
• Je moet links kijken. = You must look left.

That is why kijken appears at the end of the clause.

Both can exist, but links kijken is very natural and common in Dutch.

Here links works as an adverb meaning to the left / leftward. Dutch often uses direction words this way:

• rechts kijken = look right
• links afslaan = turn left
• rechts gaan = go right

Naar links kijken is possible, but links kijken is shorter and more idiomatic in everyday traffic language.

In this sentence, ook als means even if.

So:

• ook als het fietspad vrij lijkt = even if the cycle path seems clear

It introduces a condition that does not change the instruction. In other words: you still have to look left first.

A literal word-for-word reading might suggest also if, but in natural English here it is better understood as even if.

Fietspad is a compound noun:

• fiets = bicycle
• pad = path

Together:

• fietspad = cycle path / bike lane / bicycle path

The whole word takes the gender of the last part, and pad is a het-word:

• het pad
• therefore het fietspad

So the sentence correctly says:

• het fietspad

Here vrij means clear, open, or unoccupied.

So het fietspad vrij lijkt means:

• the cycle path seems clear
• the bike lane looks empty

It does not mean free in the sense of costing nothing.

Dutch vrij can have several meanings depending on context, such as:

• free / available
• clear / unobstructed
• off work / not busy

In traffic language, vrij often means clear to go or not blocked by traffic.

Because als introduces a subordinate clause, and in subordinate clauses Dutch typically sends the finite verb to the end.

Main clause word order:

• Het fietspad lijkt vrij.

Subordinate clause word order:

• ... als het fietspad vrij lijkt.

So the change happens because of the conjunction als.

Also note that lijkt is singular because the subject is singular:

• het fietspad = singular

It can be either, but in a sentence like this it is often general.

Dutch je can mean:

• you = the person being addressed
• you / one / people in general = a general instruction

In traffic rules or safety instructions, je often works like English you in general advice:

• You should always look both ways.

So here it sounds like a general instruction to the reader, rider, or driver.

Because that part is a separate subordinate clause added to the main instruction.

Main clause:

• Bij de volgende kruising moet je eerst links kijken

Subordinate clause:

• ook als het fietspad vrij lijkt

The comma helps show the boundary between the two parts. In Dutch, commas are commonly used to separate a main clause from a following subordinate clause like this, especially when it adds extra condition or clarification.