How do I pull singe cell RNA sequencing data from GEO database? I am new to R and computational biology. I am trying to look through a published data set to check for gene expression for my own project. I am having trouble finding materials to teach me how to analyze single cell RNA sequencing data on R from the GEO NCBI database.

This is the data that I am trying to access https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE138651

I would appreciate any directions or suggestions for tutorials.

Thanks!
The simplest would be using a count matrix (at the end of the link you have shared, section "Supplementary file"). For example GSE138651_Vagal_WholeNodoseSeq_raw.mtx.gz corresponds to "raw" count matrices obtained after mapping and counting the reads. This file, along with the GSE138651_barcodes.tsv.gz and GSE138651_genes.tsv.gz can be used to "read" the data into R; to that end there are many options in the form of packages, Seurat is one of the best documented and hence is beginner-friendly.