How many cpu cores does each vcpu has?

1 vCPU = access to 1 core, 2 vCPUs = access to 2 cores, etc…

At least on Ubuntu/Debian, the /proc/cpuinfo has a separate entry for each CPU core. So when you scan through the file you might see cpu cores: 1 but there is a separate entry for each core. For example:

root@ubuntu-s-2vcpu-4gb-lon1-01:~# cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 63
model name	: Intel(R) Xeon(R) CPU E5-2650L v3 @ 1.80GHz
stepping	: 2
microcode	: 0x1
cpu MHz		: 1799.998
cache size	: 30720 KB
physical id	: 0
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl eagerfpu pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single retpoline kaiser vnmi ept fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat
bugs		: cpu_meltdown spectre_v1 spectre_v2
bogomips	: 3599.99
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual
power management:

processor	: 1
vendor_id	: GenuineIntel
cpu family	: 6
model		: 63
model name	: Intel(R) Xeon(R) CPU E5-2650L v3 @ 1.80GHz
stepping	: 2
microcode	: 0x1
cpu MHz		: 1799.998
cache size	: 30720 KB
physical id	: 1
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 1
initial apicid	: 1
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon rep_good nopl eagerfpu pni pclmulqdq vmx ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm invpcid_single retpoline kaiser vnmi ept fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt arat
bugs		: cpu_meltdown spectre_v1 spectre_v2
bogomips	: 3599.99
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual
power management:

Knowing that, some commandline-fu to output the number of cores is: cat /proc/cpuinfo | grep processor | wc -l

which is just finding the number of lines in cpuinfo with processor. Here’s an even more thorough answer: https://askubuntu.com/questions/724228/how-to-find-the-number-of-cpu-cores-including-virtual